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The Library 




OF 



TRINITY MEDICAL j&HOOL 



NO. 



CHEMICAL AFFARA: 



Plate /. 





DICTIONARY 



OF 



CHEMISTRY 



AND 

1 



MINERALOGY, 

WITH THEIR APPLICATIONS. 



BY ANDREW URE, M.D.F.R.S. 

PROFESSOR OF CHEMISTRY IN THE ANDERSONIAN UNIVERSITY, MEMBER OF THE GEOLOGICAL 
AND ASTRONOMICAL SOCIETIES OF LONDON, CORRESPONDENT OF THE ACADEMY OF 
NATURAL SCIENCES OF PHILADELPHIA, &C. &C. &C. 



FOURTH EDITION, 
WITH NUMEROUS IMPROVEMENTS. 




LONDON : 

PRINTED FOR THOMAS TEGG & SON, 73. CHEAPSIDE ; 

R. GRIFFIN & CO. GLASGOW; AND 

TEGG, WISE & CO. DUBLIN. 

MDCCCXXXV. 



Printed by Walker & Greig, 
Edinburgh. 



TO 

THE RIGHT HONOURABLE 

THE EARL OF GLASGOW, 

BARON ROSS OF HAWKHEAD, 
&C. &C. &C. 

LORD LIEUTENANT OF AYRSHIRE. 



MY LORD, 

WHEN I inscribe this Volume to your Lordship, it is neither 
to offer the incense of adulation, which your virtues do not need, and 
your understanding would disdain ; nor to solicit the patronage of ex- 
alted rank to a Work, which in this age and nation must seek support 
by scientific value alone. The present dedication is merely an act of 
gratitude, as pure on my part, as your Lordship's condescension and 
kindness to me have been generous and unvarying. At my outset in 
life, your Lordship's distinguished favour cherished those studious pur- 
suits which have since formed my chief pleasure and business ; and to 
your Lordship's hospitality I owe the elegant retirement, in which many 
of the following pages were written. Happy would it have been for 
their readers, could I have transfused into them a portion of that grace 
of diction, and elevation of sentiment, which I have so often been 
permitted to admire in your Lordship's family. 

I have the honour to be, 
My LORD, 

Your Lordship's most obedient 
GLASGOW, 
November 7. 1820, 

And very faithful Servant, 

ANDREW URE. 



ADVERTISEMENT 



TO THE 



FOURTH EDITION. 



I HAVE now the pleasure, for the fourth time, of offering my grateful 
acknowledgments to the Public for their effective patronage of this 
Dictionary. In submitting the Third Edition to their perusal, I imagined 
that few alterations would be required should another impression of the 
Work be demanded within two or three years. But such has been the 
activity of the Chemical world in supplying many desiderata of detail 
within this brief period, as already to furnish copious materials for 
addition and emendation. Accordingly I have felt it my duty to intro- 
duce into the following pages many articles entirely new, and to re- 
write, in whole or in part, several of those under old. titles. The quan- 
tity of letter-press has been likewise increased, notwithstanding every 
effort of condensation ; so that the volume, from its compact style of 
typography, contains as much reading as would fill four ordinary 
octavos. 

It has been my purpose to render the present Edition as exact and 
ample a transcript as circumstances would allow of the actual state of 
Chemical Science, and of its relations to Medicine, to the Phenomena 
of Nature, and to the Arts. With what success this design is executed, 
it is for the candour of my readers to decide. 



Just Published, 

IN ONE LARGE VOLUME 8VO, PRICE 16s. 

A MANUAL OF ANALYTICAL CHEMISTRY, 

COMPRISING 

INSTRUCTIONS for Detecting the Presence, and Determining the Pro- 
portions of the Constituents of CHEMICAL COMPOUNDS, including 
the Recent Discoveries and Improvements of BERZELIUS and other 
Analysts. 

BY HENRY ROSE, 

PROFESSOR OF CHEMISTRY AT BERLIN. 

Translated from the German by JOHN GRIFFIN. 



INTRODUCTION. 



IN this Introduction I shall present a GENERAL VIEW of the objects of Chemistry, 
along with a Scheme for converting the Alphabetical Arrangement adopted in this 
volume into a systematic order of study. 






THE forms of matter are numberless, and subject to incessant change. Amid all 
this variety, which perplexes the common mind, the eye of science discerns a few un- 
changeable primary bodies, by whose reciprocal actions and combinations this mar- 
vellous diversity and rotation of existence are produced and maintained. These 
bodies, having resisted every attempt to resolve them into simpler forms of matter, 
are called undecompounded, and must be regarded in the present state of our know- 
ledge as experimental elements. It is possible that the elements of nature are very 
dissimilar ; it is probable that they are altogether unknown ; and that they are so 
recondite, as for ever to elude the sagacity of human research. 

The primary substances which can be subjected to measurement and weight are 
fifty-two in number. To these, some chemists add the imponderable elements light, 
heat, electricity, and magnetism. But their separate identity is not clearly ascer- 
tained. 

Of the fifty-two ponderable principles, four, possibly five, require a distinct collo- 
cation, from the marked peculiarity of their powers and properties. These are 
named Chlorine, Oxygen, Iodine, Fluorine, and Bromine. These bodies display a 
pre-eminent activity of combination, an intense affinity for most of the other forty- 
seven bodies, which they corrode, penetrate, and dissolve ; or, by uniting with them, 
so impair their cohesive force, that they become friable, brittle, or soluble in water, 
however dense, refractory and insoluble, they previously were. Such changes, for 
example, are operated on platinum, gold, silver, and iron, by the agency of chlorine, 
oxygen, or iodine. But the characteristic feature of these archeal elements is this, 
that when a compound consisting of one of them, and one of the other forty-seven 
more passive elements, is exposed to voltaic electrization, the former is uniformly 
evolved at the positive or vitreo-electric pole, while the latter appears at the negative 
or resin o-electric pole. 

The singular strength of their attractions for the other simple forms of matter is 
also manifested by the production of heat and light, or the phenomenon of combustion, 
at the instant of their mutual combination. But this phenomenon is not characteristic ; 
for it is neither peculiar nor necessary to their action, and therefore cannot be made 
the basis of a logical arrangement. Combustion is vividly displayed in cases where 
none of these primary dissolvents is concerned. Thus certain metals combine with 
others with such vehemence as to elicit light and heat ; and many of them, by their 
union with sulphur, even in vacuo, exhibit intense combustion. Potassium burns 
distinctly in cyanogen (carburetted azote), and splendidly in sulphuretted hydrogen. 
For other examples to the same purpose, see COMBUSTIBLE and COMBUSTION. 



viii INTRODUCTION. 

And again, the phenomenon of flame does not necessarily accompany any of the 
actions of oxygen, chlorine, and iodine. Its production may be regulated at the 
pleasure of the chemist, and occurs merely when the mutual combination is rapidly 
effected. Thus chlorine or oxygen will unite with hydrogen, either silently and 
darkly, or with fiery explosion, as the operator shall direct. 

Since, therefore, the quality of exciting or sustaining combustion is not peculiar to 
these electro-positive elements ; since it is not indispensable to their action on other 
substances, but adventitious and occasional we perceive the inaccuracy of that classi- 
fication which sets these three or four bodies apart under the denomination of sup- 
porters of combustion ; as if combustion could not be supported without them, and 
as if the support of combustion was their indefeasible attribute, the essential con- 
comitant of their action. On the contrary, every change which they can produce by 
their union with other elementary matter, may be effected without the phenomenon 
of combustion. See section 5th of article COMBUSTION. 

The other forty-seven elementary bodies have, with the exception of azote, (the 
solitary incombustible), been grouped under the generic name of combustibles. But 
in reality combustion is independent of the agency of all these bodies, and therefore 
combustion may be produced without any combustible. Can this absurdity form a 
basis of chemical classification ? The decomposition of euchlorine, as well as of the 
chloride and iodide of azote, is accompanied with a tremendous energy of heat and 
light ; yet no combustible is present. The same examples are fatal to the theoretical 
part of Black's celebrated doctrine of latent heat. His facts are, however, invaluable, 
and not to be controverted, though the hypothetical thread used to connect them be 
finally severed. 

To the term combustible is naturally attached the idea of the body so named afford- 
ing the heat and light. Of this position, it has been often remarked, that we have 
no evidence whatever. We know, on the other hand, that oxygen, the incombusti- 
ble, could yield, from its latent stores, in Black's language, both the light and heat 
displayed in combustion ; for mere mechanical condensation of that gas in a syringe 
causes their disengagement. A similar condensation of the combustible hydrogen 
occasions, I believe, the evolution of no light. From all these facts it is plain, that 
the above distinction is unphilosophical, and must be abandoned. In truth, every 
insulated or simple body has such an appetency to combine with, or is solicited with 
such attractive energy by, other forms of matter, whether the actuating forces be 
electro-attractive or electrical, that the motion of the particles constituting the 
change, if sufficiently rapid, may always produce the phenomenon of combustion. 

Of the forty-seven electro-negative elements, forty-one are metallic, and six non- 
metallic. 

The latter group may be arranged into three pairs : 

1st, The gaseous bodies, HYDROGEN and AZOTE. 

2<f, The fixed and infusible solids, CARBON and BORON. 

3d, The fusible and volatile solids, SULPHUR and PHOSPHORUS. 

The forty-two metallic bodies are distinguishable by their habitudes with oxygen, 
into two great divisions, the BASIFIABLE and ACIDIFIABLE metals. The former are 
thirty-five in number, the latter seven. 

Of the thirty-five metals which 'yield by their union with oxygen salifiable bases, 
three are convertible into alkalis, nine into earths, and twenty-three into ordinary 
metallic oxides. Some of the latter, however, by a maximum dose of oxygen, seem 
to graduate into the acidifiable group, or at least cease to form salifiable bases. 

We shall now delineate a general Chart of Chemistry, enumerating its various 
leading objects in a somewhat tabular form, and pointing out their most important 



INTRODUCTION. ix 

relations, so that the readers of this Dictionary may have- it in their power to study- 
its contents in a systematic order. 

CHEMISTRY 

is the science which treats of the specific differences in the nature of bodies, and the 
permanent changes of constitution to which their mutual actions give rise. 

This diversity in the nature of bodies is derived either from the AGGREGATION or 
COMPOSITION of their integrant particles. The state of aggregation seems to depend on 
the relation between the cohesive attraction of these integrant particles, and the anta- 
gonizing force of heat. Hence the three general forms of solid, liquid, and gaseous, 
under one or other of which every species of material being may be classed. 

For instruction on these general forms of matter, the student ought to read, lst f 
The early part of the article ATTRACTION ; 2d, CRYSTALLIZATION ; 3d, That part of 
CALORIC entitled " Of the change of state produced in bodies by caloric, independent 
of change of composition." He may then peruse the introductory part of the article 
GAS, and BALANCE, and LABORATORY. He will now be sufficiently prepared for the 
study of the rest of the article CALORIC, as well as that of its correlative subjects, 
TEMPERATURE, THERMOMETER, EVAPORATION, CONGELATION, CRYOPHORUS, DEW, 
and CLIMATE. The order now prescribed will be found convenient. In the article 
CALORIC there are a few discussions which the beginner may perhaps find somewhat 
difficult. These he may pass over at the first reading, and resume their considera- 
tion in the sequel. After Caloric he may peruse LIGHT, and the first three sections 
of ELECTRICITY. 

The article COMBUSTION will be most advantageously examined after he has be- 
come acquainted with some of the diversities of COMPOSITION ; viz. with the four 
electro-positive dissolvents, oxygen, chlorine, bromine, and iodine ; and the six non- 
metallic electro-negative elements, hydrogen, azote, carbon, boron, sulphur, and phos- 
phorus. Let him begin with oxygen, and then peruse, for the sake of connexion, 
hydrogen, and water. Should he wish to know how the specific gravity of gaseous 
matter is ascertained, he may consult the fourth section of the article GAS. 

The next subject to which he should direct his attention is CHLORINE ; on which 
he will meet with ample details in the present Work. This article will bear a second 
perusal. It describes a series of the most splendid efforts ever made by the sagacity 
of man, to unfold the chemical mysteries of nature. In connexion with it, he may 
read the articles CHLOROUS and CALORIC OXIDES, or the protoxide and deutoxide of 
Chlorine. Let him next study the copious articles BROMINE and IODINE, from be- 
ginning to end. 

Carbon, boron, sulphur, phosphorus, and azote, must now come under review. 
Related closely with the first, he will study the carbonous oxide, carburetted and sub- 
carburetted hydrogen. What is known of the element boron will be speedily learned ; 
and he may then enter on the examination of sulphur, sulphuretted hydrogen, and 
carburet of sulphur. Phosphorus andphosphuretted hydrogen, with nitrogen or azote, 
and its oxides and chlorides, will form the conclusion of the first division of chemical 
study, which relates to the elements of most general interest and activity. The 
general articles Combustible, Combustion, and Safe-Lamp, may now be read with 
advantage ; as well as the remainder of the article Attraction, which treats of affinity. 

Since in the present work the alkaline and earthy salts are annexed to their respec- 
tive acids, it will be proper, before commencing the study of the latter, to become 
acquainted with the alkaline and earthy bases. 

The order of reading may therefore be the following : first, The general article 



x INTRODUCTION. 

alkali, then potash and potassium, soda and sodium, lithia and ammonia. Next, the 
general article earth ; afterwards calcium and lime, barium and baryta, strontia f mag- 
nesia, alumina, silica, glucina, zirconia, yttria, and thorina. 

Let him now peruse the general articles acid and salt ; and then the non-metallic 
oxygen acids, with their subjoined salts, in the following order : sulphuric, sulphu- 
rous ; hyposulphurous, and hyposulphuric ; phosphoric, phosphorous, and hypophos- 
phorous ; carbonic and chlorocarbonous ; boracic ; and, lastly, the nitric and nitrous. 
The others may be studied conveniently with the hydrogen group. The order of 
perusing them may be, the muriatic (hydrochloric of M. Gay Lussac), chloric, and 
perchloric; the hydriodic, iodic, and chloriodic ; the fluoric, fluoboric, and Jluosilicic ; 
the prussic (hydrocyanic of M. Gay Lussac), ferroprussic, chloroprussic, and sulphu- 
roprussic. The hydrosulphurous arid hydrotellurous are discussed in this Dictionary 
under the names of sulphuretted hydrogen, and telluretted hydrogen. These com- 
pound bodies possess acid powers, as well perhaps as arsenuretted hydrogen. It 
would be ad visable to peruse the article cyanogen either before or immediately after 
prussic acid. 

As to the vegetable and animal acids, they may be read either in their alphabetical 
order, or in any other which the student or his teacher shall think fit. 

The metallic acids fall naturally under metallic chemistry ; on the study of which 
I have nothing to add to the remarks contained in the general article METAL. Along 
with each metal in its alphabetical place, its native state, or ores, may be studied. 
See ORES. 

The chemistry of organized matter may be methodically examined by perusing, first 
of all, the article vegetable kingdom, with the various products of vegetation there 
enumerated ; and then the article animal kingdom, with the subordinate animal pro- 
ducts, and adipocere. 

The article analysis may now be consulted ; then mineral WATERS ; equivalents 
(chemical), and analysis of ores. 

The mineralogical department should be commenced with the general articles mine- 
ralogy and crystallography ; after which the different species and varieties may be ex- 
amined under their respective titles. The enumeration of the genera of M. Mohs, 
given in the first article, will guide the student to a considerable extent in their me- 
thodical consideration. Belonging to mineralogy are the subjects blowpipe, geology, 
with its subordinate rocks, ores, and meteorolite. 

The medical student may read with advantage the articles acid (arsenious), anti- 
mony, bile, blood, calculus (urinary), the sequel of copper, digestion, gall-stones, gal- 
vanism, intestinal concretion, lead, mercury, poisons, respiration, urine, Sfc. 

The agriculturist will find details^not unworthy of his attention, under the articles 
absorbent, analysis of soils, carbonate, lime, manure, and soils. 

Among the discussions interesting to manufacturers are, acetic and other acids, 
alcohol, alum, ammonia, beer, bleaching, bread, caloric, chloride ofiAWE, coal, coal- 
gas, distillation, dyeing, ether, fat, fermentation, glass, ink, iron, ores, potash, pottery, 
salt, soap, soda, steel, sugar, tanning, 8fc. 

The general reader will find, it is hoped, instruction, blended with entertainment, 
in the articles aerostation, air, climate, combustion, congelation, dew, electricity, equi- 
valents, galvanism, geology, light, meteorolite, rain, and several other articles formerly 
noticed. 



CM : E M ; CA.li A : AT ITS 



i //. 




CHBMICAI, AFJPARATUSo 



Plate ///. 




CHEMICAL APPARATUS o Tia**ir: 

^llllillil.lilllIBB ' 




PLATE VI. 




PLATE VII. 





PLATE VTII. 







lfy.7. 




Ha. 8. 




PI.ATE IX. 



Fig. 3. 




DICTIONARY 



OF 



CHEMISTRY. 



ABSORBENT. 

ABRAZITE, ZEAGONITE, or GIS- 
MONDINE. A mineral which occurs 
in semi-globular masses, and in octahedral 
crystals with a square base. Colour greyish- 
white, sometimes with a tinge of blue. Yields 
to the nail, but occasionally hard enough to 
scratch glass. Brittle. Fracture conchoidal. 
Translucent or transparent. Constituents: 
silica 41. 4; lime 48.6; alumina 2.5; mag- 
nesia 1.5; oxide of iron 2.5. Reduced by 
acids to a jelly, without effervescence. Loses 
its lustre, and becomes friable before the blow- 
pipe. It is found in the cavities of volcanic 
rocks, with calcareous spar, at Capo di Bove 
near Rome. Phillips' Mineralogy. 

ABSORBENT. An epithet introduced 
into chemistry by the physicians, to designate 
such earthy substances as seemed to check 
diarrhoea by the mere absorption of the re- 
dundant liquids. In this sense it is obsolete 
and unfounded. The faculty of withdrawing 
moisture from the air is not confined to sub- 
stances which unite with water in every pro- 
portion, as the strong acids, dry alkalis, alka- 
line earths, and deliquescent salts, but is pos- 
sessed by insoluble and apparently inert bo- 
dies, in various degrees of force.' Hence the 
term absorbent merits a place in chemical 
nomenclature. 

The substance whose absorbent power is 
to be examined, after thorough desiccation 
before a fire, is immediately transferred into 
a phial furnished with a well ground stopper. 
When it is cooled, a portion of it is put into 
a large wide-mouthed bottle, where it is close- 
ly confined for some time. A delicate hygro- 
meter being then introduced, indicates on its 
scale the dryness produced in the enclosed air, 
which should have been previously brought to 
the point of extreme humidity, by suspending 



ABSORBENT. 

a moistened rag within the bottle. The fol- 
lowing Table exhibits the results of experi- 
ments made by Professor Leslie: 

Alumina causes a dryness of 84 degrees. 
Carbonate of magnesia, - 75 
Carbonate of lime, > - 70 
Silica, - - 40 

Carbonate of baryta, - 32 
Carbonate of strontia, - 23 
Pipeclay, - 85 

Greenstone, or trap in powder, 80 
Shelly sea sand, 70 

Clay indurated by torrefaction, 35 
Clay strongly ignited, - 8 
Greenstone ignited, - 23 
Quartz do. - - 19 

Decomposed greenstone, 86 

Greenstone resolved into soil, 92 
Garden mould, 95 

The more a soil is comminuted by labour and 
vegetation, the greater is its absorbent power. 
This ingenious philosopher infers, that the 
fertility of soils depends chiefly on their dis- 
position to imbibe moisture ; and illustrates 
this idea by recent and by disintegrated lava. 
May not the finely divided state most pene- 
trable by the delicate fibres of plants, derive 
its superior power of acting on atmospherical 
vapour from the augmentation of its surface 
or the multiplication of the points of contact ? 
In similar circumstances 100 gr. of the 
following organic substances absorb the fol- 
lowing quantities of moisture : Ivory 7 gr. 
boxwood 14, down 16, wool 18, beech 28. 
Charcoal, and other porous solids of a fibrous 
texture, have the faculty of absorbing gases 
in a remarkable degree ; for an account of 
M. de Saussure's excellent experiments on 
A 



ACHROMATIC. 



ACIDS. 



which subject, see the article GAS in this Dic- 
tionary. Leslie on Heat and Moisture. 

ABSORPTION. The passage of a gas, 
or vapour, into a liquid or solid substance ; 
or of a liquid into the pores of a solid. 

ACANTICONE. See PISTACITE. 

ACE RATES. The acer campestre, or 
common maple, yields a milky sweetish sap, 
containing a salt with basis of lime, possessed, 
according to Scherer, of peculiar properties. 
It is white, semitransparent, not altered by 
the air, and soluble in nearly 100 parts of 
cold, or 50 of boiling water. 

ACERIC ACID. See ACID (AcERic). 

ACESCENT. Substances which become 
sour spontaneously, as vegetable and animal 
juices, or infusions. The suddenness with 
which this change is effected during a thunder 
storm, even in corked bottles, has not been 
accounted for. In morbid states of the sto- 
mach, also, it proceeds with astonishing ra- 
pidity. It is counteracted by bitters, antacids, 
and purgatives. 

ACETATES. Salts formed by the com- 
bination of acetic acid with alkalis, earths, 
and metallic oxides. See ACID ( ACETIC). 

ACETIC ACID. See ACID (ACETIC). 

ACETOMETER. An instrument for 
estimating the strength of vinegars. It is 
described under ACID ( ACETIC). 

ACETOUS. Of or belonging to vinegar. 
See ACID ( ACETIC). 

ACH1RITE. Emerald Malachite; a 
mineral consisting of oxide of copper, carbo- 
nate of lime, silica and water. It dissolves 
in glass of borax, and imparts a green colour 
to it. It is soluble without effervescence in 
muriatic acid. 

ACHMIT. A mineral 6rst distinguished 
by Bergraeister Strom. It has a brownish- 
black or reddish-brown colour, is spotted, 
greyish-green in the fracture, externally of a 
glassy lustre, and in the transverse fracture 
glimmering. Translucent in small fragments. 
It has four cleavages, two of which are parallel 
to the sides of an oblique four-sided prism, 
and the other two, less obvious, are parallel 
to the truncations of the acute lateral edges. 
The fracture is small grained. Specific gra- 
vity 5.24. Hardness such as to scratch glass. 
It is likewise crystallized in oblique four-sided 
prisms, with truncated lateral edges, and very 
sharp four-sided terminal faces, the edges of 
which correspond with the lateral edges of the 
oblique prism. The sides are channelled in 
the direction of their length. According to 
Berzelius this mineral contains silica 55.25, 
peroxide of iron 31.25, protoxide of manga- 
nese 1.08, lime 0.72, soda 10.40, oxide of 
titanium a trace. He considers it as a bisi- 
licate of soda, combined with a bisilicate of 
iron. 

ACHROMATIC. Telescopes formed of 
a combination of lenses, which in a great 
measure correct the optical aberration arising 



from the various colours of light, are called 
achromatic telescopes. 

ACIDS. The most important class of 
chemical compounds. In the generalization 
of facts presented by Lavoisier and the asso- 
ciated French chemists, it was the leading 
doctrine that acids resulted from the union of 
a peculiar combustible base called the radical, 
with a common principle technically called 
oxygen, or the acidifier. This general posi- 
tion was founded chiefly on the phenomena 
exhibited in the formation and decomposition 
of sulphuric, carbonic, phosphoric, and nitric 
acids ; and was extended by a plausible ana- 
logy to other acids whose radicals were un- 
known. 

" I have already shewn," says Lavoisier, 
" that phosphorus is changed by combustion 
into an extremely light, white, flaky matter. 
Its properties are likewise entirely altered by 
this transformation : from being insoluble in 
water, it becomes not only soluble, but so 
greedy of moisture as to attract the humidity 
of the air with astonishing rapidity. By this 
means it is converted into a liquid, consider- 
ably more dense, and of more specific gravity 
than water. In the state of phosphorus before 
combustion, it had scarcely any sensible taste ; 
by its union with oxygen, it acquires an ex- 
tremely sharp and sour taste : in a word, from 
one of the class of combustible bodies, it is 
changed into an incombustible substance, and 
becomes one of those bodies called acids. 

" This property of a combustible substance, 
to be converted into an acid by the addition 
of oxygen, we shall presently find belongs to 
a great number of bodies. Wherefore strict 
logic requires that we should adopt a com- 
mon term for indicating all those operations 
which produce analogous results. This is the 
true way to simplify the study of science, as it 
would be quite impossible to bear all its spe- 
cific details in the memory if they were not 
classically arranged. For this reason we shall 
distinguish the conversion of phosphorus into 
an acid by its union with oxygen, and in ge- 
neral every combination of oxygen with a com- 
bustible substance, by the term oxygenation : 
from this I shall adopt the verb to oxygenate, 
and of consequence shall say, that in oxyge- 
nating phosphorus, we convert it into an acid. 

" Sulphur also, in burning, absorbs oxygen 
gas : the resulting acid is considerably heavier 
than the sulphur burnt; its weight is equal 
to the sum of the weights of the sulphur 
which has been burnt, and of the oxygen 
absorbed ; and, lastly, this acid is weighty, 
incombustible, and miscible with water in all 
proportions. 

" I might multiply these experiments, and 
show, by a numerous succession of facts, that 
all acids are formed by the combustion of 
certain substances ; but I am prevented from 
doing so in this place by the plan which I 
have laid down, of proceeding only from facts 



ACIDS 



IN GENERAL. 



already ascertained to such as are unknown, 
and of drawing my examples only from cir- 
cumstances already explained. In the mean 
time, however, the examples above cited may 
suffice for giving a clear and accurate con- 
ception of the manner in which acids are 
formed. By these it may be clearly seen that 
oxygen is an element common to them all, 
and which constitutes or produces their aci- 
dity j and that they differ from each other 
according to the several natures of the oxy- 
genated or acidified substances. We must, 
therefore, in every acid, carefully distinguish 
between the acidifiable base, which M. de 
Morveau calls the radical, and the acidifying 
principle or oxygen." Elements, p. 115. 
" Although we have not yet been able either 
to compose or to decompound this acid of sea 
salt, we cannot have the smallest doubt that 
it, like all other acids, is composed by the 
union of oxygen with an acidifiable base. 
We have, therefore, called this unknown sub- 
stance the muriatic base, or muriatic radical." 
P. 122. 5th Edit. 

Berthollet's sound discrimination led him 
to maintain that Lavoisier had given too much 
latitude to the idea of oxygen being the uni- 
versal acidifying principle. " In fact," says 
he, " it is carrying the limits of analogy too 
far to infer, that all acidity, even that of the 
muriatic, fluoric, and boracic acids, arises 
from oxygen, because it gives acidity to a 
great number of substances. Sulphuretted 
hydrogen, which really possesses the proper- 
ties of an acid, proves directly that acidity 
is not in all cases owing to oxygen. There 
is no better foundation for concluding that 
hydrogen is the principle of alkalinity, not 
only in the alkalis properly so called, but 
also in magnesia, lime, strontia, and baryta, 
because ammonia appears to owe its alkalinity 
to hydrogen. 

" These considerations prove that oxygen 
may be regarded as the most usual principle 
of acidity, but that this species of affinity for 
the alkalis may belong to substances which 
do not contain oxygen ; that we must not, 
therefore, always infer, from the acidity of a 
substance, that it contains oxygen, although 
this may be an inducement to suspect its 
existence in it ; still less should we conclude, 
because a substance contains oxygen, that it 
must have acid properties ; on the contrary, 
the acidity of an oxygenated substance shows 
that the oxygen has only experienced an in- 
complete saturation in it, since its properties 
remain predominant." , 

Amid the just views which pervade the 
early part of this quotation from Berthollet, 
it is curious to remark the solecism with 
which it terminates. For after maintaining 
that acidity may exist independent of oxygen, 
and that the presence of oxygen does not ne- 
cessarily constitute acidity, he concludes by 



considering acidity as the attribute of unsatu- 
rated oxygen. 

This unwarrantable generalization of the 
French chemists concerning oxygen, which 
had succeeded Stahl's equally unwarrantable 
generalization of a common principle of com- 
bustibility in all combustible bodies, was first 
experimentally combated by Sir H. Davy, in 
a series of admirable dissertations published 
in the Philosophical Transactions. 

His first train of experiments was instituted 
with the view of operating by voltaic electricity 
on muriatic and other acids freed from water. 
Substances which are now known by the names 
of chlorides of phosphorus and tin, but which 
he then supposed to contain dry muriatic acid, 
led him to imagine that intimately combined 
water was the real acidifying principle, since 
acid properties were immediately developed in 
the above substances by the addition of that 
fluid, though previously they exhibited no acid 
powers. In July 1810, however, he advanced 
those celebrated views concerning acidifica- 
tion, which, in the opinion of the best judges, 
display an unrivalled power of scientific re- 
search. The conclusions to which these led 
him were incompatible with the general hypo- 
thesis of Lavoisier. He demonstrated that 
oxymuriatic acid is, as far as our knowledge 
extends, a simple substance, which may be 
classed in the same order of natural bodies as 
oxygen gas, being determined like oxygen to 
the positive surface in voltaic combinations, 
and like oxygen combining with inflammable 
substances, producing light and heat. The 
combinations of oxymuriatic acid with inflam- 
mable bodies were shewn to be analogous to 
oxides and acids in their properties and powers 
of combination, but to differ from them in 
being for the most part decomposable by 
water ; and finally, that oxymuriatic acid has 
a stronger attraction for most inflammable 
bodies than oxygen. His preceding decom- 
position of the alkalis and earths having 
evinced the absurdity of that nomenclature 
which gives to the general and essential con- 
stituent of alkaline nature the term oxygen or 
acidifier ; his new discovery of the simplicity of 
oxymuriatic acid showed the theoretical sys- 
tem of chemical language to be equally vicious 
in another respect. Hence this philosopher 
most judiciously discarded the appellation 
oxymuriatic acid, and introduced in its place 
the name chlorine, which merely indicates an 
obvious and permanent character of the sub- 
stance, its greenish-yellow colour. The more 
recent investigations of chemists on fluoric, 
hydriodic, and hydrocyanic acids, have brought 
powerful analogies in support of the chloridic 
theory, by showing that hydrogen alone can 
convert certain undecompounded bases into 
acids well characterized, without the aid of 
oxygen. Dr Murray indeed endeavoured to 
revive and new-model the early opinion of Sir 



ACIDS 



IN GENERAL. 



H. Davy, concerning the necessity of the pre- 
sence of water, or its elements, to the consti- 
tution of acids. He conceived that many acids 
are ternary compounds of a radical with oxy- 
gen and hydrogen ; but that the two latter in- 
gredients do not necessarily exist in them in 
the state of water. Oil of vitriol, for instance, 
in this view, instead of consisting of 81.5 real 
acid, and 18.5 water, in 100 parts, may be 
regarded as a compound of 32.6 sulphur -{- 
65.2 oxygen -j- 2.2 hydrogen. When it is 
saturated with an alkaline base, and exposed 
to heat, the hydrogen unites to its equivalent 
quantity of oxygen to form water, which eva- 
porates, and the remaining oxygen and the sul- 
phur combine with the base. But when the 
acid is made to act on a metal, the oxygen 
partly unites to it, and hydrogen alone escapes. 

" Nitric acid, in its highest state of con- 
centration, is not a definite compound of real 
acid with about a fourth of its weight of 
water, but a ternary compound of nitrogen, 
oxygen, and hydrogen. Phosphoric acid is 
a triple compound of phosphorus, oxygen, 
and hydrogen ; and phosphorous acid is the 
proper binary compound of phosphorus and 
oxygen. The oxalic, tartaric, and other vege- 
table acids, are admitted to be ternary com- 
pounds of carbon, oxygen, and hydrogen; and 
are therefore in strict conformity to the doc- 
trine now illustrated. 

" AVelation of the elements of bodies to 
acidity is thus discovered different from what 
has hitherto been proposed. When a series 
of compounds exist, which have certain com- 
mon characteristic properties, and when these 
compounds all contain a common element, 
we conclude, with justice, that these proper- 
ties are derived more peculiarly from the ac- 
tion of this element. On this ground La- 
voisier inferred, by an ample induction, that 
oxygen is a principle of acidity. Berthollet 
brought into view the conclusion, that it is 
not exclusively so, from the examples of prus- 
sic acid and sulphuretted hydrogen. In the 
latter, acidity appeared to be produced by the 
action of hydrogen. The discovery by Gay 
Lussac of the compound radical cyanogen, 
and its conversion into prussic acid by the 
addition of hydrogen, confirmed this conclu- 
sion ; and the discovery of the relations of 
iodine still further established it. And now, 
if the preceding views are just, the system 
must be still further modified. While each 
of these conclusions is just to a certain ex- 
tent, each of them requires to be limited in 
some of the cases to which they are applied ; 
and while acidity is sometimes exclusively 
connected with oxygen, sometimes with hy- 
drogen, the principle must also be admitted, 
that it is more frequently the result of their 
combined operation. 

" There appears even sufficient reason to 
infer, that, from the united action of these 
elements, a higher degree of acidity is ac- 



quired than from the action of either alone. 
Sulphur affords a striking example of this. 
With hydrogen it forms a weak acid. With 
oxygen it also forms an acid, which, though 
of superior energy, still does not display 
much power. With hydrogen and oxygen 
it seems to receive the acidifying influence 
of both, and its acidity is proportionally ex- 
alted. 

" Nitrogen, with hydrogen, forms a com- 
pound altogether destitute of acidity, and 
possessed even of qualities the reverse. With 
oxygen, in two definite proportions, it forms 
oxides ; and it is doubtful if, in any propor- 
tion, it can establish with oxygen an insulated 
acid. But with oxygen and hydrogen in union 
it forms nitric acid, a compound more per- 
manent, and of energetic action." 

It is needless to give at more detail Dr 
Murray's speculations, which, supposing them 
plausible in a theoretical point of view, seem 
barren in practice. It is sufficiently singular, 
that, in an attempt to avoid the transforma- 
tions which, on his notion of the chloridic 
theory, a little moisture operates on common 
salt, instantly changing it from chlorine and 
sodium into muriatic acid and soda, Dr 
Murray should have actually multiplied, with 
one hand, the very difficulties which he had 
laboured, with the other, to remove. 

He thinks it doubtful if nitrogen and oxy- 
gen can alone form an insulated acid. Hy- 
drogen he conceives essential to its energetic 
action. What, we may ask then, exists in 
dry nitre, which contains no hydrogen ? Is 
it nitric acid, or merely two of its elements, 
in want of a little water to furnish the re- 
quisite hydrogen ? The same questions may 
be asked relative to the sulphate of potash. 
Since he conceives hydrogen necessary to 
communicate full force to sulphuric and ni- 
tric acids, the moment they lose their water 
they should lose their saturating power, and 
become incapable of retaining caustic potash 
in a neutral state. Out of this dilemma he 
may indeed try to escape, by saying, that 
moisture or hydrogen is equally essential to 
alkaline strength, and that therefore the same 
desiccation or dehydrogenation which impairs 
the acid power, impairs also that of its alka- 
line antagonist. The result must evidently 
be, that, in a saline hydrate or solution, we 
have the reciprocal attractions of a strong acid 
and alkali, while, in a dry salt, the attractive 
forces are those of relatively feeble bodies. 
On this hypothesis, the difference ought to be 
great between dry and moistened sulphate of 
potash. Carbonic acid he admits to be desti- 
tute of hydrogen ; yet its saturating power is 
very conspicuous in neutralizing dry lime. 
Again, oxalic acid, by the last analysis of 
Berzelius, as well as my own, contains no 
hydrogen : it differs from the carbonic only in 
the proportion of its two constituents. And 
oxalic acid is appealed to by Dr Murray as a 



ACIDS 



IN GENERAL. 



proof of the superior acidity bestowed by 
hydrogen. 

On what grounds he decides carbonic to 
be a feebler acid than oxalic, it is difficult 
to see. By Berthollet's test of acidity, the 
former is more energetic than the latter in 
the proportion of 100 to about 58 ; for these 
numbers are inversely as the quantity of each 
requisite to saturate a given base. If he be 
inclined to reject this rule, and appeal to the 
decomposition of the carbonates by oxalic 
acid as a criterion of relative acid power, let 
us adduce his own commentary on the sta- 
tical affinities of Berthollet, where he ascribes 
such changes, not to a superior attraction in 
the decomposing substance, but to the elastic 
tendency of that which is evolved. Ammonia 
separates magnesia from its muriatic solution 
at common temperatures ; at the boiling heat 
of water, magnesia separates ammonia. Car- 
bonate of ammonia, at temperatures under 
230, precipitates carbonate of lime from the 
muriate; at higher temperatures, the inverse 
decomposition takes place with the same in- 
gredients. If the oxalic be a more energetic 
acid than the carbonic, or rank higher in the 
scale of acidity, then, on adding to a given 
weight of liquid muriate of lime a mixture of 
oxalate and carbonate of ammonia, each in 
equivalent quantity to the calcareous salt, 
oxalate of lime ought alone to be separated. 
It will be found, on the contrary, by the test 
of acetic acid, that as much carbonate of lime 
will precipitate as is sufficient to unsettle these 
speculations. 

Finally, dry nitre, and dry sulphate of 
potash, are placed, by this supposition, in as 
mysterious a predicament as dry muriate of 
soda in the chloridic theory. Deprived of 
hydrogen, their acid and alkali are enfeebled 
or totally changed. With a little water, both 
instantly recruit their powers. In a word, 
the solid sulphuric acid of Nordhausen, and 
the dry potash of potassium, are alone suf- 
ficient to subvert this whole hypothesis of hy- 
drogenation. 

We shall introduce, under the head of 
alkali, some analogous speculations by Dr 
Murray on the influence of the elements of 

water on that class of bodies Edin. Phil 

Trans, vol. viii. part 2d. 

After these observations on the nature of 
acidity, we shall now state the general proper- 
ties of the acids. 

1 . The taste of these bodies is for the most 
part sour, as their name denotes ; and in the 
stronger species it is acrid and corrosive. 

2. They generally combine with water in 
every proportion, with a condensation of vo- 
lume and evolution of heat. 

3. With a few exceptions they are vola- 
tilized or decomposed at a moderate heat. 

4. They usually change the purple colours 
of vegetables to a bright red. 



5. They unite in definite proportions with 
the alkalis, earths, and metallic oxides, and 
form the important class of Salts. This may 
be reckoned their characteristic and indis- 
pensable property. The powers of the dif- 
ferent acids were originally estimated by their 
relative causticity and sourness, afterwards 
by the scale of their attractive force towards 
any particular base, and next by the quantity 
of the base which they could respectively 
neutralize. But Berthollet proposed the f 
converse of this last criterion as the measure 
of their powers. " The power with which 
they can exercise their acidity," he estimates 
" by the quantity of each of the acids which 
is required to produce the same effect, viz. to 
saturate a given quantity of the same alkali." 
It is therefore the capacity for saturation of 
each acid, which, in ascertaining its acidity, 
according to him, gives the comparative force 
of the affinity to which it is owing. Hence 
he infers, that the affinity of the different 
acids for an alkaline base, is in the inverse 
ratio of the ponderable quantity of each of 
them which is necessary to neutralize an equal 
quantity of the same alkaline base. An acid 
is therefore, in this view, the more powerful, 
when an equal weight can saturate a greater 
quantity of an alkali. Hence, all those sub- 
stances which can saturate the alkalis, and 
cause their properties to disappear, ought to 
be classed among the acids : in like manner, 
among the alkalis should be placed all those 
which, by their union, can saturate acidity. 
And the capacity for saturation being the 
measure of this property, it should be em- 
ployed to form a scale of the comparative 
power of alkalis as well as that of acids. 

However plausible, a priori, the opinion of 
this illustrious philosopher may be, that the 
smaller the quantity of an acid or alkali re- 
quired to saturate a given quantity of its an- 
tagonist principle, the higher should it rank 
in the scale of power and affinity, it will not, 
however, accord with chemical phenomena. 

100 parts of nitric acid are saturated by about 
36^ of magnesia, and 52^ of lime. Hence, 
by iBerthollet's rule, the powers of these earths 
ought to be inversely as their quantities, viz. 

and -; yet the very opposite effect 

ODo" t)^^" 

takes place, for lime separates magnesia from 
nitric acid. And in the present example, the 
difference of effect cannot be imputed to the 
difference of force with which the substances 
tend to assume the solid state. 

We have therefore at present no single 
acidifying principle, nor absolute criterion of 
the scale of power among the different acids ; 
nor is the want of this of great importance. 
Experiment furnishes us with the order of 
decomposition of one acido-alkaline com- 
pound by another acid, whether alone, or 
aided by temperature ; and this is all which 
practical chemistry seems to require. 



ACIDS 



IN GENERAL. 



Before entering on the particular acids, 
we shall here describe the general process by 
which M. Thenard has lately succeeded in 
communicating to many of them apparently 
a surcharge of oxygen, and thus producing a 
supposed new class of bodies, the oxygenized 
acids, which are, in reality, combinations of 
the ordinary acids with oxygenized water, 
or with the deutoxide of hydrogen. The 
first notice of these new compounds ap- 
peared in the Ann. de Chimie et Physique, 
viii. 306. for July 1818; since which time 
several additional communications of a very 
interesting nature have been made by the 
same celebrated chemist. He has likewise 
formed a compound of water with oxygen, in 
which the proportion of the latter principle is 
doubled, or 616 times its volume is added. 
The methods of oxygenizing the liquid acids 
and water agree in this, that deutoxide of 
barium is formed first of all, from which the 
above liquids, by a subsequent process, derive 
their oxygen. He prescribes the following 
precautions, without which success will be 
only partial : 

] . Nitrate of baryta should first be ob- 
tained perfectly pure, and, above all, free 
from iron and manganese. The most certain 
means of procuring it is to dissolve the ni- 
trate in water, to add to the solution a small 
excess of baryta water, to filter and crys- 
tallize. 2. The pure nitrate is to be decom- 
posed by heat. This ought not to be done 
in a common earthenware retort, because it 
contains too much of the oxides of iron and 
manganese, but in a perfectly white porcelain 
retort. Four or five pounds of nitrate of 
baryta may be decomposed at once, and the 
process will require about three hours. The 
baryta thus procured will contain a consi- 
derable quantity of silex and alumina ; but it 
will have only very minute traces of manga- 
nese and iron, a circumstance of essential 
importance. 3. The baryta, divided by a 
knife into pieces as large as the end of the 
thumb, should then be placed in a luted tube 
of glass. This tube should be long, and 
large enough to contain from 2 to 3 Ibs. 
It is to be surrounded with fire, and heated 
to dull redness, and then a current of dry 
oxygen gas is to be passed through it. How- 
ever rapid the current, the gas is completely 
absorbed; so that when it passes by the 
small tube, which ought to terminate the 
larger one, it may be concluded that the 
deutoxide of barium is completed. It is, 
however, right to continue the current for 
seven or eight minutes more. Then the tube 
being nearly cold, the deutoxide, which is of 
a light grey colour, is taken out, and pre- 
served in stoppered bottles. When this is 
moistened it falls to powder, without much 
increase of temperature. If in this state it 
be mixed with seven or eight times its weight 
of water, and a dilute acid be poured in, it 



dissolves gradually by agitation, without the 
evolution of any gas. The solution is neutral, 
or has no action on turnsole or turmeric. 
When we add to this solution the requisite 
quantity of sulphuric acid, a copious preci- 
pitate of baryta falls, and the filtered liquor 
is merely water, holding in solution the oxy- 
genized acid, or deutoxide of hydrogen, com- 
bined with the acid itself. 

The class of acids has been distributed into 
three orders, according as they are derived 
from the mineral, the vegetable, or the animal 
kingdom. But a more specific distribution 
is now requisite. They have also been ar- 
ranged into those which have a single, and 
those which have a compound basis or radical, 
But this arrangement is not only vague, but 
liable in other respects to considerable objec- 
tions. The chief advantage of a classification 
is to give general views to beginners in the 
study, by grouping together such substances 
as have analogous properties or composition. 
These objects, it is hoped, will be tolerably 
well attained by the following divisions and 
subdivisions. 

Division 1st, Acids from inorganic nature, 
or which are procurable without having re- 
course to animal or vegetable products. 

Division 2d, Acids elaborated by means of 
organization. 

The first group is subdivided into three 
families: 1st, Oxygen acids; 2d, Hydrogen 
acids ; 3d, Acids destitute of both these sup- 
posed acidifiers. 



Family 1st. 
Section 1st, 

1. Boracic. 

2. Bromic. 

3. Carbonic. 

4. Chloric. 

5. Perchloric. 

6. Chlorocarbonic. 

7. lodous. 

8. Nitrous. 

9. Hyponitric. 

10. Nitric. 

11. Hyponitrous. 



-Oxygen Acids. 
Non-metallic. 

12. lodic. 

13. lodo-sulphuric. 

14. Hypophosphorous. 

15. Phosphorous. 

16. Phosphatic. 

17. Phosphoric. 

18. Hyposulphurous. 

19. Sulphurous. 

20. Hyposulphuric. 

21. Sulphuric. 

22. Cyanic. 



Section 2d, Oxygen Acids Metallic. 

1. Arsenic. 8. Manganesous. 

2. Arsenious. 9. Molybdic. 

3. Antimonious. 10. Molybdous. 

4. Antimonic. 11. Selenic. 

5. Chromic. 12. Selenious. 

6. Columbic. 13. Titanic. 

7. Manganesic. 14. Tungstic. 

Family 2d. Hydrogen Acids. 

1. Fluoric. 6. Hydrobromic. 

2. Hydriodic. 7. Hydroselenic. 

3. Hydrochloric, or 8. Hydrocyanic. 

Muriatic. 9. Hydrosulphurous. 

4. Ferrocyanic. 10. Hydrotellurous. 

5. Fluotitanic. 11. Sulphocyanic. 



ACID 



ACETIC. 



Family 3d. Acids without oxygen or 
hydrogen. 

1. Chloriodic. 3. Fluoboric. 

2. Chlorocyanic. 4. Fluosilicic. 

Division 2d. Acids of organic origin. 

1. Abietic. 35. Malic. 

2. Aceric. 36. Meconic. 

3. Acetic. 37. Menispermic? 

4. Aloetic. 38. Margaric. 

5. Amniotic. 39. Melassic. 

6. Amylic. 40. Mellitic. 

7. Benzoic. 41. Moroxylic. 

8. Boletic. 42. Mucic? 

9. Bombic. 43. Nanceic? 

10. Butyric. 44. Nitro-leucic. 

11. Camphoric. 45. Nitro-saccharic. 

12. Capric, Caproic. 46. Oleic. 

13. Carbazotic. 47. Oxalic. 

14. Caseic. 48. Pectic. 

15. Cevadic. 49. Phocenic. 

16. Cholesteric. 50. Pinic. 

17. Citric. 51. Purpuric. 

18. Croconic. 52. Pyrocitric. 

19. Delphinic. 53. Pyrolithic. 

20. Ellagic? 54. Pyromalic. 

21. Formic. 55. Pyrotartaric. 

22. Fulminic. 56. Rosacic. 

23. Fungic. 57. Saclactic. 

24. Gallic. 58. Sebacic. 

25. Glancic. 59. Silvic. 

26. Hircic. 60. Solanic. 

27. Hydroxanthic. 61. Stearic. 

28. Indigoic. 62. Suberic. 

29. Igasuric. 63. Succinic. 

30. Kinic. 64. Sulpho- 

31. Laccic. naphthalic. 

32. Lactic. 65. Sulphovinic. 

33. Lampic. 66. Tartaric. 

34. Lithic or Uric. 67. Vegeto-sulphuric. 
The acids of this last division are all decom- 
posable at a red heat, and afford generally car- 
bon, hydrogen, oxygen, and in some few cases 
also nitrogen. The mellitic is found like am- 
ber in wood coal, and, like it, is undoubtedly 
of organic origin. We shall treat of them all 
in alphabetical order, only joining those acids 
together which graduate, so to speak, into 
each other, as hyposulphurous, sulphurous, 
hyposulphuric, and sulphuric. 

ACID (ABIETIC). A substance, crys- 
tallizing in square plates, soluble in alcohol, 
and capable of forming salts with the alkalis, 
extracted from the resin of the Pinus Abies 
by M. Baup of Lausanne. 

ACID (ACERIC). A peculiar acid said 
to exist in the juice of the maple. It is decom- 
posed by heat, like the other vegetable acids. 

ACID (ACETIC). The same acid which, 
in a ve*-y dilute and somewhat impure state, 
is called vinegar. 

This acid is found combined with potash 
in the juices of a great many plants ; particu- 
larly the sambucus nigra, phoenix dactilifera, 
galium verum, and rhus typhinus. Sweat, 



urine, and even fresh milk, contain it. It is 
frequently generated in the stomachs of dys- 
peptic patients. Almost all dry vegetable 
substances, and some animal, subjected in 
close vessels to a red heat, yield it copiously. 
It is the result likewise of a spontaneous fer- 
mentation, to which liquid vegetable and ani- 
mal matters are liable. Strong acids, as the 
sulphuric and nitric, develope the acetic by 
their action on vegetables. It was long sup- 
posed, on the authority of Boerhaave, that 
the fermentation which forms vinegar is uni- 
formly preceded by the vinous. This is a 
mistake. Cabbages sour in water, making 
sour crout ; starch, in starch-makers' sour 
waters ; and dough itself, without any pre- 
vious production of wine. 

The varieties of acetic acids known in com- 
merce are four: 1st, Wine vinegar; 2d, 
Malt vinegar ; 3d, Sugar vinegar ; 4th, Wood 
vinegar. We shall describe first the mode of 
making these commercial articles, and then 
that of extracting the absolute acetic acid of 
the chemist, either from these vinegars, or 
directly from chemical compounds, of which 
it is a constituent. 

The following is the plan of making vine- 
gar at present practised in Paris. The wine 
destined for vinegar is mixed in a large tun 
with a quantity of wine lees, and the whole 
being transferred into cloth sacks, placed 
within a large iron-bound vat, the liquid 
matter is extruded through the sacks by super- 
incumbent pressure. What passes through 
is put into large casks, set upright, having 
a small aperture in their top. In these it is 
exposed to the heat of the sun in summer, or 
to that of a stove in winter. Fermentation 
supervenes in a few days. If the heat should 
then rise too high, it is lowered by cool air, 
and the addition of fresh wine. In the skil- 
ful regulation of the fermentative temperature 
consists the art of making good wine vinegar. 
In summer, the process is generally completed 
in a fortnight ; in winter, double the time is 
requisite. The vinegar is then run off' into 
barrels, which contain several chips of birch- 
wood. In about a fortnight it is found to be 
clarified, and is then fit for the market. It 
must be kept in close casks. 

The manufacturers at Orleans prefer wine 
of a year old for making vinegar. But if 
by age the wine has lost its extractive mat- 
ter, it does not readily undergo the acetous 
fermentation. In this case, acetification, as 
the French term the process, may be deter- 
mined, by adding slips of vines, bunches of 
grapes, or green woods. It has been asserted 
that alcohol, added to fermentable liquor, 
does not increase the product of vinegar. 
But this is a mistake. Stahl observed long 
ago, that if we moisten roses or lilies with 
alcohol, and place them in vessels in which 
they are stirred from time to time, vinegar 
will be formed. He also informs us, if after 



ACID 



I 



ACETIC. 



abstracting the citric acid from lemon juice 
by crabs' eyes (carbonate of lime), we add a 
little alcohol to the supernatant liquid, and 
place the mixture in a proper temperature, 
vinegar will be formed. 

Chaptal says, that two pounds of weak 
spirits, sp. gr. 0.985, mixed with 300 grains 
of beer yeast and a little starch water, pro- 
duced extremely strong vinegar. The acid 
was developed on the fifth day. The same 
quantity of starch and yeast, without the 
spirit, fermented more slowly, and yielded a 
weaker vinegar. A slight motion is found 
to favour the formation of vinegar, and to 
endanger its decomposition after it is made. 
Chaptal ascribes to agitation the operation of 
thunder ; though it is well known, that when 
the atmosphere is highly electrified, beer is 
apt to become suddenly sour, without the 
concussion of a thunder-storm. In cellars 
exposed to the vibrations occasioned by the 
rattling of carriages, vinegar does not keep 
well. The lees, which had been deposited by 
means of isinglass and repose, are thus jum^ 
bled into the liquor, and make the fermenta- 
tion recommence. 

Almost all the vinegar of the north of 
France being prepared at Orleans, the manu- 
facture of that place has acquired such cele- 
brity, as to render their process worthy of a 
separate consideration. 

The Orleans casks contain nearly 400 
pints of wine. Those which have been al- 
ready used are preferred. They are placed 
in three rows, one over another, and in the 
top have an aperture of two inches diameter, 
kept always open. The wine for acetification 
is kept in adjoining casks, containing beech 
shavings, to which the lees adhere. The 
wine thus clarified is drawn off to make vine- 
gar. One hundred pints of good vinegar, 
boiling hot, are first poured into each cask, 
and left there for eight days. Ten pints of 
wine are mixed in, every eight days, till the 
vessels are full. The vinegar is allowed to 
remain in this state fifteen days; before it is 
exposed to sale. 

The used casks, called mothers, are never 
emptied more than half, but are successively 
filled again, to acetify new portions of wine. 
In order to judge if the mother works, the 
vinegar-makers plunge a spatula into the li- 
quid ; and according to the quantity of froth 
which the spatula shows, they add more or 
less wine. In summer, the atmospheric heat 
is sufficient. In winter, stoves heated to about 
75 Fahr. maintain the requisite temperature 
in the manufactory. 

In some country districts, the people keep 
in a place where the temperature is mild and 
equable, a vinegar cask, into which they pour 
such wine as they wish to acetify ; and it is 
always preserved full, by replacing the vine- 
gar drawn off by new wine. To establish 
this household manufacture, it is only neces- 



sary to buy at first a small cask of good 
vinegar. 

At Gand a vinegar from beer is made, in 
which the following proportions of grain are 
found to be most advantageous : 

1880 Paris Ibs. malted barley. 
700 wheat. 

500 buckwheat 

These grains are ground, mixed, and boiled, 
along with twenty-seven casks-full of river 
water, for three hours. Eighteen casks of 
good beer for vinegar are obtained. By a 
subsequent decoction, more fermentable li- 
quid is extracted, which is mixed with the 
former. The whole brewing yields 3000 Eng- 
lish quarts. 

In this country, vinegar is usually made 
from malt. By mashing with hot water, 
100 gallons of wort are extracted in less than 
two hours from 1 boll of malt. When the 
liquor has fallen to the temperature of 75 
Fahr. 4< gallons of the barm of beer are 
added. After thirty-six hours it is racked 
off into casks, which are laid on their sides, 
and exposed, with their bung-holes loosely 
covered, to the influence of the sun in sum- 
mer ; but in winter they are arranged in a 
stove-room. In three months this vinegar is 
ready for the manufacture of sugar of lead. 
To make vinegar for domestic use, however, 
the process is somewhat different. The above 
liquor is racked off into casks placed upright, 
having a false cover pierced with holes fixed 
at about a foot from their bottom. On this 
a considerable quantity of rape, or the refuse 
from the makers of British wine, or otherwise 
a quantity of low-priced raisins, is laid. The 
liquor is turned into another barrel every 
twenty-four hours, in which time it has be- 
gun to grow warm. Sometimes, indeed, the 
vinegar is fully fermented, as above, without 
the rape, which is added towards the end, to 
communicate flavour. Two large casks are 
in this case worked together, as is described 
long ago by Boerhaave, as follows : 

" Take two large wooden vats, or hogs- 
heads, and in each of these place a wooden 
grate or hurdle, at the distance of a foot from 
the bottom. Set the vessel upright, and on 
the grate place a moderately close layer of 
green twigs, or fresh cuttings of the vine. 
Then fill up the vessel with the footstalks of 
grapes, commonly called the rape, to the top 
of the vessel, which must be left quite open. 

" Having thus prepared the two vessels, 
pour into them the wine to be converted into 
vinegar, so as to fill one of them quite up, 
and the other but half full. Leave them 
thus for twenty-four hours, and then fill up 
the half filled vessel with liquor from that 
which is quite full, and which will now in its 
turn only be left half full. Four-and-twenty 
hours afterwards repeat the same operation, 
and thus go on, keeping the vessels alternately 
full and half full during twenty-four hours, 



ACID 



g 



ACETIC. 



till the vinegar be made. On the second or 
third day there will arise in the half filled 
vessel a fermentative motion, accompanied 
with a sensible heat, which will gradually in- 
crease from day to day. On the contrary, 
the fermenting motion is almost imperceptible 
in the full vessel ; and as the two vessels are 
alternately full and half full, the fermentation 
is by this means in some measure interrupted, 
and is only renewed every other day in each 
vessel. 

" When this motion appears to have entire- 
ly ceased, even in the half filled vessel, it is a 
sign that the fermentation is finished ; and 
therefore the vinegar is then to be put into 
casks close stopped, and kept in a cool place. 

" A greater or less degree of warmth ac- 
celerates or checks this, as well as the spiritu- 
ous fermentation. In France it is finished 
in about fifteen days, during the summer ; 
but if the heat of the air be very great, and 
exceed the twenty- fifth degree of Reaumur's 
thermometer (88 Fahr.), the half filled 
vessel must be filled up every twelve hours ; 
because, if the fermentation be not so checked 
in that time, it will become violent, and the 
liquor will be so heated, that many of the 
spirituous parts, on which the strength of the 
vinegar depends, will be dissipated, so that 
nothing will remain after the fermentation but 
a vapid liquor, sour indeed, but effete. The 
better to prevent the dissipation of the spi- 
rituous parts, it is a proper and usual pre- 
caution to close the mouth of the half filled 
vessel in which the liquor ferments, with a 
cover made of oak wood. As to the full 
vessel, it is always left open, that the air may 
act freely on the liquor it contains ; for it is 
not liable to the same inconveniences, because 
it ferments very slowly." 

Good vinegar may be made from a weak 
syrup, consisting of 18 oz. of sugar to every 
gallon of water. The yeast and rape are to 
be here used as above described. Whenever 
the vinegar (from the taste and flavour) is 
considered to be complete, it ought to be 
decanted into tight barrels or bottles, and 
well secured from access of air. A momen- 
tary ebullition before it is bottled is found 
favourable to its preservation. In a large 
manufactory of malt vinegar, a considerable 
revenue is derived from the sale of yeast to 
the bakers. 

Vinegar obtained by the preceding methods 
has more or less of a brown colour, and a 
peculiar but rather grateful smell. By distil- 
lation in glass vessels, the colouring matter, 
which resides in a mucilage, is separated, but 
the fragrant odour is generally replaced by 
an empyreumatic one. The best French wine 
vinegars, and also some from malt, contain a 
little alcohol, which comes over early with 
the watery part, and renders the first product 
of distillation scarcely denser, sometimes even 
less dense, than water. It is accordingly 



rejected. Towards the end of the distillation 
the empyreuma increases. Hence only the 
intermediate portions are retained as distilled 
vinegar. Its specific gravity varies from 1 .005 
to 1.015, while that of common vinegar of 
equal strength varies from 1.010 to 1.025. 

A crude vinegar has been long prepared 
for the calico printers, by subjecting wood 
in iron retorts to a strong red heat. The 
following arrangement of apparatus has been 
found to answer well. A series of cast-iron 
cylinders, about 4 feet diameter, and 6 feet 
long, are built horizontally in brick-work, so 
that the flame of one furnace may play round 
about two cylinders. Both ends project a 
little from the brick-work. One of them 
has a disc of cast-iron well fitted and firmly 
bolted to it, from the centre of which disc an 
iron tube, about 6 inches diameter, proceeds, 
and enters at a right angle the main tube of 
refrigeration. The diameter of this tube 
may be from 9 to 14 inches, according to the 
number of cylinders. The other end of the 
cylinder is called the mouth of the retort. 
This is closed by a disc of iron, smeared 
round its edge with clay-lute, and secured 
in its place by wedges. The charge of wood 
for such a cylinder is about 8 cwt. The 
hard woods, oak, ash, birch, and beech, are 
alone used ; fir does not answer. The beat 
is kept up during the day-time, and the fur- 
nace is allowed to cool during the night. 
Next morning the door is opened, the char- 
coal removed, and a new charge of wood is 
introduced. The average product of crude 
vinegar called pyrolignous acid is 35 gallons. 
It is much contaminated with tar ; is of a 
deep brown colour; and has a sp. gr. of 
1.025. Its total weight is therefore about 
300 Ibs. But the residuary charcoal is found 
to weigh no more than one-fifth of the wood 
employed. Hence nearly one-half of the 
ponderable matter of the wood is dissipated 
in incondensable gases. Count Rumford 
states, that the charcoal is equal in weight to 
more than four-tenths of the wood from 
which it is made. The Count's error seems 
to have arisen from the slight heat of an oven 
to which his wood was exposed in a glass 
cylinder. The result now given is the expe- 
rience of an eminent manufacturing chemist 
at Glasgow. The crude pyrolignous acid is 
rectified by a second distillation in a copper 
still, in the body of which about 20 gallons 
of viscid tarry matter are left from every 100. 
It has now become a transparent brown vi- 
negar, having a considerable empyreumatic 
smell, and a sp. gr. of 1.013. Its acid powers 
are superior to those of the best household 
vinegar, in the proportion of 3 to 2. By 
redistillation, saturation with quicklime, eva- 
poration of the liquid acetate to dryness, and 
gentle torrefaction, the empyreumatic matter 
is so completely dissipated, that on decom- 
posing the calcareous salt by sulphuric acid, 



ACID 



10 



ACETIC. 



a pure, perfectly colourless, and grateful vine- 
gar rises in distillation. Its strength will be 
proportional to the concentration of the de- 
composing acid. 

The acetic acid of the chemist may be 
prepared in the following modes : 1st, Two 
parts of fused acetate of potash, with one of 
the strongest oil of vitriol, yield, by slow dis- 
tillation from a glass retort into a refrige- 
rated receiver, concentrated acetic acid. A 
small portion of sulphurous acid, which con- 
taminates it, may be removed by redistilla- 
tion from a little acetate of lead. 2d, Or 
4 parts of good sugar of lead, with 1 part of 
sulphuric acid treated in the same way, afford 
a slightly weaker acetic acid. 3d, Gently 
calcined sulphate of iron, or green vitriol, 
mixed with sugar of lead in the proportion 
of 1 of the former to 2| of the latter, and 
carefully distilled from a porcelain retort into 
a cooled receiver, may be also considered a 
good economical process. Or without dis- 
tillation, if 100 parts of well dried acetate of 
lime be cautiously added to 60 parts of strong 
sulphuric acid, diluted with 5 parts of water, 
and digested for 24 hours, and strained, a 
good acetic acid, sufficiently strong for every 
ordinary purpose, will be obtained. 

The distillation of acetate of copper or of 
lead per se, has also been employed for ob- 
taining strong acid. Here, however, the 
product is mixed with a portion of the fra- 
grant pyro-acetic spirit, which it is trouble- 
some to get rid of. Undoubtedly the best 
process for the strong acid is that first de- 
scribed, and the cheapest the second or third. 
When of the utmost possible strength, its 
sp. gravity is 1.062. At the temperature of 
50 F. it assumes the solid form, crystalliz- 
ing in oblong rhomboidal plates. It has an 
extremely pungent odour, affecting the nos- 
trils and eyes even painfully when its vapour 
is incautiously snuffed up. Its taste is emi- 
nently acid and acrid. It excoriates and in- 
flames the skin. 

The purified wood vinegar, which is used 
for pickles and culinary purposes, has com- 
monly a specific gravity of about 1.009; 
when it is equivalent in acid strength to good 
wine or malt vinegar of 1.014. It contains 
about 5 J 5 of its weight of absolute acetic 
acid, and of water. An excise duty of 
4d. is levied on every gallon of vinegar of 
the above strength. This, however, is not 
estimated directly by its sp. gr. but by the 
sp. gr. which results from its saturation with 
quicklime. The decimal number of the sp. 
gr. of the calcareous acetate is nearly double 
that of the pure wood vinegar. Thus J.009 
in vinegar, becomes 1.018 in liquid acetate. 
But the vinegar of fermentation =1.014 will 
become only 1.023 in acetate, from which 
if 0.005 be subtracted for mucilage or ex- 
tractive, the remainder will agree with the den- 
sity of the acetate from wood. A glass hy- 



drometer of Fahrenheit's construction is used 
for finding the specific gravities. It consists 
of a globe about 3 inches diameter, having a 
little ballast ball drawn out beneath, and a 
stem above of about 3 inches long, contain- 
ing a slip of paper with a transverse line in 
the middle, and surmounted with a little cup 
for receiving weights or poises. The experi- 
ments on which this instrument, called an 
acetometer, is constructed, have been detailed 
in the sixth volume of the Journal of Science. 
They do not differ essentially from those of 
Mollerat. The following points were deter- 
mined by this chemist. The acid of sp. gr. 
1.063 requires 2^ times its weight of crys- 
tallized subcarbonate of soda for saturation ; 
whence M. Thenard regards it as a com- 
pound of 1 1 of water and 89 of real acid in 
the 100 parts. Combined with water in the 
proportion of 100 to 112.2, it does not 
change its density, but it then remains liquid 
several degrees below the freezing point of 
water. By diluting it with a smaller quan- 
tity of water, its sp. gr. augments, a circum- 
stance peculiar to this acid. It is 1.079, or 
at its maximum, when the water forms one- 
third of the weight of the acid Ann. de 
Chimie, torn. 66. 

The following Table is given by Messrs 
Taylor, as the basis of their acetometer : 

Revenue proof acid, called by the manu- 
facturer No. 24. 

sp. gr. .0085 contains real acid in 100, 5 
.0170 10 

.0257 ... 15 

.0320 20 

.0470 ... - 30 
.0580 40 

An acetic acid of very considerable strength 
may also be prepared by saturating perfectly 
dry charcoal with common vinegar, and then 
distilling. The water easily comes off, and 
is separated at first ; but a stronger heat is 
required to expel the acid. Or by exposing 
vinegar to very cold air, or to freezing mix- 
tures, its water separates in the state of ice, 
the interstices of which are occupied by a 
strong acetic acid, which may be procured by 
draining. The acetic acid, or radical vinegar 
of the apothecaries, in which they dissolve a 
little camphor or fragrant essential oil, has 
a specific gravity of about 1.070. It contains 
fully I part of water to 2 of the crystallized 
acid. The pungent smelling salt consists of 
sulphate of potash moistened with that acid. 
Acetic acid acts on tin, iron, zinc, copper, 
and nickel ; and it combines readily with the 
oxides of many other metals, by mixing a 
solution of their sulphates with that of an 
acetate of lead. 

This acid, as it exists in the acetates of 
baryta and of lead, has been analyzed by 
MM. Gay Lussac and Thenard, and also by 
Berzelius. 

Gay Lussac found 50.224 carbon, 5.629 



ACID 



11 



ACETIC. 



hydrogen, and 44. 147 oxygen ; or, in other 
terms, 50. 224 carbon, 46.911 of water, or its 
elementary constituents, and 2.863 oxygen 
in excess. 

Berzelius, 46.83 carb. 6.33hydrog. and 
46.82 oxygen, in the hundred parts. 

Dr Prout, in his excellent paper on Ali- 
mentary Substances, (Phil Transact. 1827, 
Part ii.), finds that the hydrogen and oxygen 
of acetic acid exist in it, in the proportions 
in which they form water ; his proportions 
of the constituents agreeing with the results 
of Berzelius, or carbon 47.05, water 52.95, 
in 100 parts. 

Their methods are described under VEGE- 
TABLE (ANALYSIS). By saturating known 
weights of bases with acetic acid, and ascer- 
taining the quantity of acetates obtained after 
cautious evaporation to dryness, Berzelius 
obtained with lime (3.56) 6.5 for the prime 
equivalent of acetic acid, and with yellow 
oxide of lead 6. 432. 

Acetic acid dissolves resins, gum resins, 
camphor, and essential oils. Its odour is em- 
ployed in medicine to relieve nervous head- 
ache, fainting fits, or sickness occasioned by 
crowded rooms. In a slightly dilute state, 
its application has been found to check he- 
morrhagy from the nostrils. Its anticonta- 
gious powers are now little trusted to. It 
is very largely used in calico-printing. Mo- 
derately rectified pyrolignous acid has been 
recommended for the preservation of animal 
food ; but the empyreumatic taint it com- 
municates to bodies immersed in it, is not 
quite removed by their subsequent ebullition 
in water. See ACID (PYROLIGNOUS). 

Acetic acid and common vinegar are some- 
times fraudulently mixed with sulphuric acid 
to give them strength. This adulteration may 
be detected by the addition of a little chalk, 
short of their saturation. With pure vinegar 
the calcareous base forms a limpid solution, 
but with sulphuric acid a white insoluble 
gypsum. Muriate of baryta is a still nicer 
test. British fermented vinegars are allowed 
by law to contain a little sulphuric acid, but 
the quantity is frequently exceeded. Copper 
is discovered in vinegars by supersaturating 
them with ammonia, when a fine blue colour 
is produced ; and lead by sulphate of soda, 
hydrosulphurets, and sulphuretted hydrogen. 
None of these should produce any change on 
genuine vinegar. See LEAD. 

Acetic acid dissolves deutoxide of barium 
without effervescence. By precipitating the 
baryta with sulphuric acid, there remains an 
oxygenized acid, which, being saturated with 
potash, and heated, allows a great quantity of 
oxygen gas to escape. Therfe is disengaged 
at the same time a notable quantity of carbo- 
nic acid gas. This shows that the oxygen, 
when assisted by heat, unites in part with the 
carbon, and doubtless likewise with the hy- 



drogen, of the acid. It is in fact acetic deut- 
oxide of hydrogen. 

Salts consisting of the several bases, united 
in definite proportions to acetic acid, are called 
acetates. They are characterized by the pun- 
gent smell of vinegar, which they exhale on 
the affusion of sulphuric acid ; and by their 
yielding on distillation in a moderate red heat 
a very light, odorous, and combustible liquid 
called pyro-acetic (SPIRIT) ; which see. They 
are all soluble in water ; many of them so 
much so as to be uncry stall izable. About 
30 different acetates have been formed, of 
which only a very few have been applied to 
the uses of life. 

The acetic acid unites with all the alkalis 
and most of the earths ; and with these bases 
it forms compounds, some of which are crys- 
tallizable. The salts it forms are distinguish- 
ed by their great solubility ; their decompo- 
sition by fire, which carbonizes them; the 
spontaneous alteration of their solution ; and 
their decomposition by a great number of 
acids, which extricate from them the acetic 
acid in a concentrated state. It unites like- 
wise with most of the metallic oxides. 

With baryta, the saline mass, by sponta- 
neous evaporation, crystallizes in fine trans- 
parent prismatic needles, of a bitterish acid 
taste, which do not deliquesce when exposed 
to the air, but rather effloresce. 

With potash this acid unites, and forms a 
deliquescent salt scarcely crystallizable, called 
formerly foliated earth of tartar, and regene- 
rated tartar. The solution of this salt, even 
in closely stopped vessels, is spontaneously 
decomposed. 

With soda it forms a crystallizable salt, 
which does not deliquesce. 

The salt formed by dissolving chalk or 
other calcareous earth in distilled vinegar, 
has a sharp bitter taste, and appears in the 
form of silky crystals. 

The acetate of strontia has a sweet taste, 
is very soluble, and is easily decomposed by 
a strong heat. 

The salt formed by uniting vinegar with 
ammonia, anciently called Spirit of Minde- 
rerus, is generally in a liquid state, and is 
commonly believed not to be crystallizable. 
It nevertheless may be reduced into the form 
of small needle-shaped crystals, when this 
liquor is evaporated to the consistence of a 
syrup. 

With magnesia the acetic acid forms a 
viscid saline mass, which does not shoot into 
crystals, but remains deliquescent, has a taste 
sweetish at first, and afterwards bitter, and is 
soluble in spirit of wine. 

Glucine is readily dissolved by acetic acid. 
This solution, as Vauquelin informs us, does 
not crystallize ; but is reduced by evaporation 
to a gummy substance, which slowly becomes 
dry and brittle ; retaining a kind of ductility 



ACID 



12 



ARSENIC. 



for a long time. It has a saccharine and 
pretty strongly astringent taste, in which that 
of vinegar however is distinguishable. 

Yttria dissolves readily in acetic acid, and 
the solution yields by evaporation crystals of 
acetate of yttria. These have commonly the 
form of thick six-sided plates, and are not 
altered by exposure to the air. 

Acetate of alumina is commonly made by 
adding gradually to a boiling solution of alum 
in water a solution of acetate of lead, till no 
further precipitate ensues. The sulphate of 
lead having subsided, decant the supernatant 
liquor, evaporate, and the acetate of alumina 
may be obtained in small needle-shaped crys- 
tals, having a strong styptic and acetous taste. 
This salt is of great use in dyeing and calico- 
printing. See ALUMINA. 

Acetate of zirconia may be formed by pour- 
ing acetic acid on newly precipitated zirconia. 
It has an astringent taste. It does not crys- 
tallize; but when evaporated to dryness, forms 
a powder, which does not attract moisture 
from the air. It is very soluble both in water 
and alcohol ; and is not so easily decomposed 
by heat as nitrate of zirconia. 

Concerning the action of vinegar on alco- 
hol, see ETHER. 

M. Vauquelin has found that acetic acid 
may be combined with volatile oils. See 
OILS (VOLATILE). 

See SPIRIT (PYRO- ACETIC). 

Vinegar dissolves the true gums, and partly 
the gum resins, by means of digestion. 

See SALT, for a tabular view of the con- 
stitution of the ACETATES. 

ACID (ALGETIC). The name, hardly 
appropriate, given by M. Liebeg to the bitter 
of aloes ; a substance supposed by him to be 
a compound of carbazotic acid and a peculiar 
resinous- like matter. The bitter of aloes may 
be formed in large quantity, by acting upon 
aloes with nitric acid of the sp. grav. 1.25. 
The substance obtained forms a purple salt 
with potash, but little soluble, and precipitates 
the salts of baryta, lead, and peroxide of iron, 
of a deep purple colour. Ann. de Chimie, 
xxx vii. 171. 

ACID (AMNIOTIC). On evaporating 
the liquor amnii of the cow to one-fourth, 
Vauquelin and Buniva found that crystals 
form in it by cooling. These crystals, when 
washed with a little water, are white and 
shining, slightly acid to the taste, redden lit- 
mus paper, and are a little more soluble in hot 
than cold water. With the alkalis this acid 
forms very soluble salts, but it does not de- 
compose the carbonate without the assistance 
of heat. 

Dr Prout could not find this acid in the 
amniotic liquor of the cow, though he sought 
for it with much pains. Hence its existence 
is questionable. 

ACID(AMYLIC). This new acid com- 
pound of carbon and oxygen has been des- 



cribed by M. Tunnermann in Trommsdorff's 
Journal. Equal parts of starch and black 
oxide of manganese are to be well mixed, and 
put into a retort so as to fill one-fourth of it, 
and then a third equal part of water added, 
and made to moisten the mass equably. A 
receiver being adapted, heat is applied, and 
three parts of muriatic acid are gradually add- 
ed through a feeding tube. The product is 
impure amylic acid, which is saturated with 
carbonate of lime, and evaporated so as to 
yield crystals of amylate of that base. These, 
purified by further crystallization, are de- 
composed by 73 per cent of sulphuric acid, 
whence, by distillation, pure amylic acid is 
obtained. It is sour, reddens vegetable blues, 
readily evaporates with a sharp odour resem- 
bling hydrocyanic acid. Its salts are mostly 
soluble, and even deliquescent. They reduce 
nitrate of silver and muriate of gold. The 
amylate of lime occurs in octangular crystals 
mingled with plates. It consists of 42.16 
lime, and 57.84 amylic acid. Amylate of 
barytes forms quadrilateral prisms, and con- 
sists of 57.29 baryta, and 29.24 amylic acid, 
with 13.47 water. The salts of potash, soda, 
and ammonia, are deliquescent. The ulti- 
mate constituents of amylic acid are said to 
be 2.5 carbon, and 3 oxygen. 

ACIDS (ANTIMONIC AND ANTI- 
MONIOUS). See ANTIMONY. 

ACID (ARSENIC). We are indebted to 
Scheele for the discovery of this acid, though 
Macquer had before noticed its combinations. 
It may be obtained by various methods. If 
six parts of nitric acid be poured on one of 
the concrete arsenious acid, or white arsenic 
of the shops, in the pneumato-chemical ap- 
paratus, and heat be applied, nitrous gas will 
be evolved, and a white concrete substance, 
differing in its properties from the arsenious 
acid, will remain in the retort. This is the 
arsenic acid. It may be equally procured by 
means of aqueous chlorine, or by heating 
concentrated nitric acid with twice its weight 
of the solution of the arsenious acid in muri- 
atic acid. The concrete acid should be ex- 
posed to a dull red heat for a few minutes. 
In either case an acid is obtained that does 
not crystallize, but attracts the moisture of 
the air, has a sharp caustic taste, reddens 
blue vegetable colours, is fixed in the fire, 
and of the specific gravity of 3.391. 

If the arsenic acid be exposed to a red heat 
in a glass retort, it melts and becomes trans- 
parent, but assumes a milky hue on cooling. 
If the heat be increased, so that the retort 
begins to melt, the acid boils, and sublimes 
into the neck of the retort. If a covered 
crucible be used instead of a glass retort, and 
a violent heat applied, the acid boils strongly, 
and in a quarter of an hour begins to emit 
fumes. These, on being received in a glass 
bell, are found to be arsenious acid ; and a 
small quantity of a transparent glass, difficult 



ACID 



13 



ARSENIC. 



to fuse, will be found lining the sides of the 
crucible. This is arseniate of alumina- 
Combustible substances decompose this 
acid, and eliminate metallic arsenic. 

With phosphorus, phosphoric acid is ob- 
tained, and a phosphuret of arsenic, which 
sublimes. 

According to Lagrange, two parts of water 
are sufficient to dissolve one of arsenic acid. 
It cannot be crystallized by any means ; but 
on evaporation assumes a thick honey-like 
consistence. 

Arsenic acid combines with the earthy and 
alkaline bases, and forms salts very different 
from those furnished by the arsenious acid. 

All these arseniates are decomposable by 
charcoal, which separates arsenic from them 
by means of heat. 

Berzelius, from the result of accurate ex- 
periments on the arseniates of lead and baryta, 
infers the prime equivalent of arsenic acid to 
be 14.4569, oxygen being 1.0. 

On this supposition, Berzelius's insoluble 
salts will consist of two primes of base and one 
of acid ; and the acid itself will be a com- 
pound of 5 of oxygen = 5 -J- 9.5 of the me- 
tallic base = 14.5; for direct experiments 
have shewn it to consist of 100 metal, and 
about 53 oxygen. But 153 : 100 : : 14.5 : 
9.5 nearly. 

While Proust and Berzelius concur in as- 
signing the proportion of 53 oxygen to 100 
metal in this acid, Thenard states its com- 
position at 56.25 to 100, and Dr Thomson 
at 61.4 to 100. By the latter authority, its 
prime equivalent becomes 4.75 metal -j- 3 
oxygen = 7.75 ; and that of arsenious acid 
4.75 + 2=6.75. 

All its salts, with the exception of those of 
potash, soda, and ammonia, are insoluble in 
water ; but except arseniate of bismuth, and 
one or two more, very soluble in an excess 
of arsenic acid. Hence, after baryta or 
oxide of lead has been precipitated by this 
acid, its farther addition redissolves the pre- 
cipitate. This is a useful criterion of the 
acid, joined to its reduction to the metallic 
state by charcoal, and the other characters 
already detailed. Sulphuric acid decomposes 
the arseniates at a low temperature, but the 
sulphates are decomposed by arsenic acid at 
a red heat, owing to the greater fixity of the 
latter. Phosphoric, nitric, muriatic, and 
fluoric acids, dissolve, and probably convert 
into subsalts, all the arseniates. The whole 
of them, as well as arsenic acid itself when 
decomposed at a red heat by charcoal, yield 
the characteristic garlic smell of the metallic 
vapour. Nitrate of silver gives a pulverulent 
brick-coloured precipitate with arsenic acid. 
The acid itself does not disturb the transpa- 
rency of a solution of sulphate of copper ; 
but a neutral arseniate gives with it a bluish- 
green precipitate ; with sulphate of cobalt a 
dirty red ; and with sulphate of nickel, an 



apple-green precipitate. These precipitates 
redissolve, on adding a small quantity of the 
acid which previously held them in solution. 
Orfila says, that arsenic acid gives, with 
acetate of copper, a bluish-white precipitate, 
but that it exercises no action either on the 
muriate or acetate of cobalt; but with the 
ammonia-muriate it gives a rose-coloured pre- 
cipitate. Arsenic acid ought to be accounted 
a more violent poison than even the arsenious. 
According to Mr Brodie, it is absorbed, and 
occasions death by acting on the brain and the 
heart. 

A solution of pure arsenic acid mixed with 
common sugar powdered, becomes in some 
hours of a reddish colour, then of a magnifi- 
cent purple : neither arsenious acid, the arse- 
nites, nor phosphoric acid, produce any simi- 
lar effect. 

Arsenic acid saturated with potash does 
not crystallize. 

The bi-arseniate of potash is fabricated 
on the great scale in Saxony, by fusing toge- 
ther equal parts of nitre and arsenious acid, 
dissolving the melted mass, and crystallizing 
the salt. The crystals are large. By the 
analysis of M. Berzelius, they consist of ar- 
senic acid 63.87, potash 26.16, water 9.97. 
Ann. de Chim. et de Phys. xix. 366. 

By Dr Thomson their composition is, arse- 
nic acid 68.5, potash 26.5, water 5. Mit- 
scherlich's statement is in accordance with 
Berzelius's equivalent number. 

With lime water this acid forms a precipi- 
tate of arseniate of lime, soluble in an excess 
of its acid, though insoluble alone. 

If arsenic acid be saturated with magnesia, 
a thick substance is formed near the point of 
saturation. 

Arseniate of baryta is insoluble, and un- 
crystallizable, but soluble in an excess of the 
acid. 

It consists, by Berzelius, of 57 baryta -|- 
43 arsenic acid. The bi-arseniate of baryta 
crystallizes. It is made by dissolving the 
neutral salt in arsenic acid. It contains 
twice the quantity of acid which exists in the 
former. 

With soda in sufficient quantity to saturate 
it, arsenic acid forms a salt crystallizable like 
the acidulous arseniate of potash. To form the 
neutral arseniate, carbonate of soda should be 
added to the acid, till the mixture be de- 
cidedly alkaline. This salt crystallizes from 
the concentrated solution. It is much more 
soluble in hot than in cold water. Pelletier 
says, that the crystals are hexaedral prisms 
terminated by planes perpendicular to their 
axis. 

100 parts of arseniate of soda are composed, 
by the experiments of Berzelius, of arsenic 
acid 29.29, soda 15.88, water 54.84. The 
triple salt, called arseniate of potash and soda, 
easily crystallizes. It consists, according to 



ACID 



AHSENIOUS. 



the same chemist, of arseniate of potash, 30.24 
Arseniate of soda, 26.65 
Water, 44. 1 1 

The bi-arseniate of soda is obtained by add- 
ing arsenic acid to the solution of the neutral 
salt, till the mixture no longer gives a preci- 
pitate with muriate of baryta. It is very 
soluble in water. It consists of 
Arsenic acid, 63.16 
Soda, 17.13 

Water, 19.71 

Combined with ammonia, arsenic acid forms 
a salt affording rhomboidal crystals analogous 
to those of the nitrate of soda. 

To form this salt, we must add ammonia to 
the concentrated solution of the acid, till a 
precipitate fall. On heating the solution, 
the precipitate is dissolved. If we set the 
liquid aside, taking care that too much of the 
ammonia does not exhale, there is formed, 
after some time, large and beautiful crystals 
of the neutral salt. The crystals which some- 
times fall during the cooling of this solution 
are a sub-arseniate. The neutral arseniate of 
ammonia decomposes in the air. It consists 
of arsenic acid, 65.28 
Ammonia, 19. 4*4 
Water, 15.28 Mitscherlich. 
Bi-arseniate of ammonia is formed by adding 
arsenic acid to ammonia till litmus paper be 
strongly reddened by the solution, and till it 
no longer precipitates muriate of baryta. We 
then obtain by evaporation crystals which do 
not change on exposure to the air. It consists, 
according to Berzelius, of arsenic acid 72.30, 
ammonia 10.77, water 16.93, in 100 parts. 
The arseniate of soda and ammonia is formed 
by mixing the two separate arseniates ; and 
the compound salt gives crystals with brilliant 
faces. If we redissolve the crystals, and then 
recrystallize, we should add a little ammonia, 
otherwise the salt will be acidulous from the 
escape of some ammonia. 

Arsenic acid does not act on gold or plati- 
na ; neither does it on mercury or silver with- 
out the aid of a strong heat ; but it oxidizes 
copper, iron, lead, tin, zinc, bismuth, anti- 
mony, cobalt, nickel, manganese, and arsenic. 

Arseniate of cobalt has been discovered 
at the lead mine of Tyne-bottom, near Alston 
in Cumberland, in the form of a rose-colour- 
ed efflorescence investing hepatic and com- 
mon pyrites. The veins are worked in a 
limestone stratum. 

This acid is not used in the arts, at least 
directly, though indirectly it forms a part of 
some compositions used in dyeing. See SALTS 
(TABLE OF). 

ACID (ARSENIOUS). Fourcroywas 
the first who distinguished by this name the 
white arsenic of the shops, which Scheele had 
proved to be a compound of the metal arsenic 
with oxygen. 

This acid, which is one of the most virulent 
poisons known, frequently occurs in a native 



state, if not very abundantly ; and it is ob- 
tained in roasting several ores, particularly 
those of cobalt In the chimneys of the fur- 
naces where this operation is conducted, it 
generally condenses in thick semitransparent 
masses ; though sometimes it assumes the form 
of a powder, or of little needles, in which state 
it was formerly called flowers of arsenic. 

The arsenious acid reddens the most sen- 
sible blue vegetable colours, though it turns 
the syrup of violets green. On exposure to 
the air it becomes opaque, and covered with 
a slight efflorescence. Thrown on incan- 
descent coals, it evaporates in white fumes, 
with a strong smell of garlic. In close vessels 
it is volatilized ; and, if the heat be strong, 
vitrified. The result of this vitrification is a 
transparent glass, capable of crystallizing in 
tetraedra, the angles of which are truncated. 
It is easily altered by hydrogen and carbon, 
which deprive it of its oxygen at a red heat, 
and reduce the metal, the one forming water, 
the other carbonic acid, with the oxygen taken 
from it ; as it is by phosphorus, and by sul- 
phur, which are .in part converted into acids 
by its oxygen, and in part form an arsenical 
phosphuret or sulphuret with the arsenic re- 
duced to the metallic state. Its specific gra- 
vity is 3. 7. 

It is soluble in thirteen times its weight of 
boiling water, but requires eighty times its 
weight of cold. The solution crystallizes, and 
the acid assumes the form of regular tetrae- 
drons, according to Fourcroy ; but according 
to Lagrange, of octaedrons, and these fre- 
quently varying in figure by different laws 
of decrement. It crystallizes much better by 
slow evaporation than by simple cooling. 

The solution is very acrid, reddens blue 
colours, unites with the earthy bases, and de- 
composes the alkaline sulphurets. Arsenious 
acid is also soluble in oils, spirits, and alco- 
hol; the last taking up from 1 to 2 per cent. 
It is composed by Berzelius of 9.5 of metal -f- 
3 oxygen ; and its prime equivalent is therefore 
12.5. But Dr Thomson considers it as a com- 
pound of 4.75 metal -f- 2 oxygen = 6.75. 

Dr Wollaston first observed, that when a 
mixture of it with quicklime is heated in a 
glass tube at a certain temperature, ignition 
suddenly pervades the mass, and metallic 
arsenic sublimes. As arseniate of lime is 
found at the bottom of the tube, we perceive 
that a portion of the arsenious acid is robbed 
of its oxygen, to complete the acidification of 
the rest. 

The action of the other acids upon the arse- 
nious is very different from that which they 
exert on the metal arsenic. By boiling, sul- 
phuric acid dissolves a small portion of it, 
which is precipitated as the solution cools. 
Nitric acid does not dissolve it, but by the 
help of heat converts it into arsenic acid. 
Aqueous chlorine acidifies it completely, so 
as to convert it into arsenic acid. 



ACID 



ARSENIOUS. 



Arsenious acid combines with the earthy 
and alkaline bases. The earthy arsenites pos- 
sess little solubility; and hence the solutions 
of baryta, strontia, and lime, form precipi- 
tates with that of arsenious acid. 

With the fixed alkalis the arsenious acid 
forms viscid arsenites, which do not crystal- 
lize, and which are decomposable by fire, 
the arsenious acid being volatilized by the 
heat. 

With ammonia it forms a salt capable of 
crystallization. 

The nitrates act on the arsenious acid in a 
very remarkable manner. On treating the 
nitrates and arsenious acid together, nitrous 
vapour is extricated : part of its oxygen is 
absorbed by the arsenious acid ; it is thus 
converted into arsenic acid, and an arseniate 
is left in the retort. The same phenomena 
take place on detonating nitrates with arse- 
nious acid; for it is still sufficiently com- 
bustible to produce a detonation, and a true 
arseniate remains at the bottom of the cruci- 
ble. It was in this way chemists formerly 
prepared their fixed arsenic, which was the aci- 
dulous arseniate of potash. The nitrate of 
ammonia exhibits different phenomena in its 
decomposition by arsenious acid, and requires 
considerable precaution. Pelletier, having 
mixed equal quantities, introduced the mix- 
ture into a large retort of coated glass, placed 
in a reverberatory furnace, with a globular 
receiver. He began with a very slight fire ; 
for the decomposition is so rapid, and the ni- 
trous vapours issue with such force, that a 
portion of the arsenious acid is carried off 
undecomposed, unless you proceed very gen- 
tly. Chlorate of potash, too, by completely 
oxidizing the arsenipus acid, converts it into 
arsenic acid, which, by the assistance of heat, 
is capable of decomposing the muriate of pot- 
ash that remains. 

Arsenious acid is used in numerous in- 
stances in the arts, under the name of white 
arsenic, or of arsenic simply. In many cases 
it is reduced, and acts in its metallic state. 

Many attempts have been made to intro- 
duce it into medicine ; but as it is known to 
be one of the most violent poisons, it is pro- 
bable that the fear of its bad effects may de- 
prive society of the advantages it might afford 
in this way. An arsenite of potash was ex- 
tensively used by the late Dr Fowler of York, 
who published a treatise on it, in intermittent 
and remittent fevers. He found it extremely 
efficacious in periodical headache, and as a 
tonic in nervous and other disorders. Exter- 
nally it has been employed as a caustic to ex- 
tirpate cancer, combined with sulphur, with 
bole, with antimony, and with the leaves of 
crowfoot ; but it always gives great pain, and 
is not unattended with danger. 

It has been more lately used as an alterative 
with advantage in chronic rheumatism. The 



symptoms which show the system to be arse- 
nified are, thickness, redness, and stiffness of 
the palpebrce, soreness of the gums, ptyalism, 
itching over the surface of the body, restless- 
ness, cough, pain at stomach, and headache. 
When the latter symptoms supervene, the ad- 
ministration of the medicine ought to be im- 
mediately suspended. It has also been recom- 
mended against chincough ; and has been used 
in considerable doses, with success, to coun- 
teract the poison of venomous serpents. 

Since it acts on the animal economy as a 
deadly poison in quantities so minute as to be 
insensible to the taste when diffused in water 
or other vehicles, it has been often given with 
criminal intentions and fatal effects. It be- 
comes therefore a matter of the utmost im- 
portance to present a systematic view of the 
phenomena characteristic of the poison, its 
operation, and consequences. 

1st, It is a dense substance, subsiding 
speedily after agitation in water. I find its 
sp. gr. to vary from 3.728 to 3.730, which is 
a little higher than the number given above : 
72 parts dissolve in 1000 of boiling water, 
of which 30 remain in it after it cools. Cold 
water dissolves, however, only T JL^ or T ^ 
of the preceding quantity. This water makes 
the syrup of violets green, and reddens litmus 
paper. Lime water gives a fine white pceci- 
pitate with it of arsenite of lime, soluble in 
an excess of the arsenious solution : sulphu- 
retted hydrogen gas, and bydrosulphuretted 
water, precipitate a golden yellow sulphuret 
of arsenic. By this means T ^^__ of arse- 
nious acid may be detected in water. This 
sulphuret, dried on a filter, and heated in a 
glass tube with a bit of caustic potash, is de- 
composed in a few minutes, and converted 
into sulphuret of potash, which remains at the 
bottom, and metallic arsenic of a bright steel 
lustre, which sublimes, coating the sides of the 
tube. The hydrosulphurets of alkalis do not 
affect the arsenious solution, unless a drop or 
two of nitric or muriatic acid be poured in, 
when the characteristic golden yellow precipi- 
tate falls. Nitrate of silver is decomposed by 
the arsenious acid, and a very peculiar yellow 
arsenite of silver precipitates; which, however, 
is apt to be redissolved by nitric acid, and 
therefore a very minute addition of ammonia 
is requisite. Even this however also, if in 
much excess, redissolves the silver precipitate. 

As the nitrate of silver is justly regarded as 
one of the best precipitant tests of arsenic, 
the mode of using it has been a subject of 
much discussion. The presence of muriate 
of soda, indeed, in the arsenical solution, ob- 
structs, to a certain degree, the operation of 
this reagent. But that salt is almost always 
present in the primce vice, and is an usual in- 
gredient in soups, and other vehicles of the 
poison. If, after the water of ammonia has 
been added, (by plunging the end of a glass 



ACID 



ARSENIOUS. 



rod dipped in it into the supposed poisonous 
liquid), we dip another rod into a solution of 
pure nitrate of silver, and transfer it into the 
arsenious solution, either a fine yellow cloud 
will be formed, or at first merely a white curdy 
precipitate. But at the second or third im- 
mersion of the nitrate rod, a central spot of 
yellow will be perceived surrounded with the 
white muriate of silver. At the next im- 
mersion this yellow cloud on the surface will 
become very conspicuous. .Sulphate of soda 
does not interfere in the least with the silver 
test. 

The ammonia-sulpha'te, or rather ammo- 
nia-acetate of copper, added in a somewhat 
dilute state to an arsenious solution, gives a 
fine grass-green and very characteristic preci- 
pitate. This green arsenite of copper, well 
washed, being acted on by an excess of sul- 
phuretted hydrogen water, changes its co- 
lour, and becomes of a brownish-red. Ferro- 
cyanate of potash changes it into a blood-red. 
Nitrate of silver converts it into the yellow 
arsenite of silver. 

Lastly, if the precipitate be dried on a filter, 
and placed on a bit of burning coal, it will 
diffuse a garlic odour. The cupreous test will 
detect TTO'OOO f tne weight of the arsenic 
in water. 

The voltaic battery, made to act by two 
wires on a little arsenious solution placed on 
a bit of window glass, developes metallic 
arsenic at the negative pole ; and if this wire 
be copper, it will be whitened like tombac. 

We may here remark, however, that the 
most elegant mode of using all these preci- 
pitation reagents is upon a plane of glass ; a 
mode practised by Dr Wollaston in general 
chemical research, to an extent, and with a 
success, which would be incredible in other 
hands than his. Concentrate by heat in a 
capsule the suspected poisonous solution, 
having previously filtered it if necessary. 
Indeed, if it be very much disguised with 
animal or vegetable matters, it is better first 
of all to evaporate to dryness, and by a few 
drops of nitric acid to dissipate the organic 
products. The clear liquid being now placed 
in the middle of the bit of glass, lines are to 
be drawn out from it in different directions. 
To one of these a particle of weak ammoniacal 
water being applied, the weak nitrate of silver 
may then be brushed over it with a hair pencil. 
By placing the glass in different lights, either 
over white paper or obliquely before the eye, 
the slightest change of tint will be perceived. 
The ammonia-acetate should be applied to 
another filament of the drop, deut-acetate of 
iron to a third, weak ammonia-acetate of co- 
balt to a fourth, sulphuretted water to a fifth, 
lime water to a sixth, a drop of violet syrup 
to a seventh, and the two galvanic wires at the 
opposite edges of the whole. Thus with one 
single drop of solution many exact experi- 
ments may be made. 



But the chief, the decisive trial or experi- 
mentum crucis remains, which is to take a little 
of the dry matter, mix it with a small pinch 
of dry black flux, put it into a narrow glass 
tube sealed at one end, and after cleansing its 
sides with a feather, urge its bottom with a 
blowpipe till it be distinctly red-hot for a mi- 
nute : Then garlic fumes will be smelt, and 
the steel-lustred coating of metallic arsenic will 
be seen in the tube about one-fourth of an inch 
above its bottom. Cut the tube across at that 
point by means of a fine file ; detach the scale 
of arsenic with the point of a penknife ; put 
a fragment of it into the bottom of a small 
wine-glass along with a few drops of ammo- 
nia-acetate of copper, and triturate them well 
together for a few minutes with a round-headed 
glass rod : The mazarine blue colour will soon 
be transmuted into a lively grass-green, while 
the metallic scale will vanish. Thus we dis- 
tinguish perfectly between a particle of me- 
tallic arsenic and one of animalized charcoal. 
Another particle of the scale may be placed 
between two smooth and bright surfaces of 
copper, with a touch of fine oil ; and whilst 
they are firmly pressed together, exposed to 
a red heat : The tombac alloy will appear as 
a white stain. A third particle may be placed 
on a bit of heated metal, and held a little 
under the nostrils, when the garlic odour will 
be recognized. No danger can be apprehend- 
ed, as the fragment need not exceed the tenth 
of a grain. 

In cases of poisoning with arsenic, says 
Berzelius, the individual may have taken the 
deadly poison, either in the pulverulent form, 
or in a state of solution. In the first case, 
we can almost always detect visible particles 
of arsenic in the contents of the stomach, or 
on its inner coat, where they are distinguished 
by dark red spots of inflammation. The fol- 
lowing method will detect the nature of these 
particles, though less than one-tenth of a grain 
in weight. A glass tube, from one-tenth to 
one-seventh of an inch in diameter, is drawn 
out at one extremity into a fine point, from 
two to three inches in length, which part ought 
not to be wider internally than the thickness of 
a coarse knitting needle, and it is then her- 
metically closed at the end. The particle of 
arsenic is moved downwards to the sealed 
point, and covered with charcoal powder: 
previously expose it to the flame of the blow- 
pipe, to drive off any moisture. The charcoal 
is now heated to redness in the flame of a spirit 
lamp, and then the arsenic is brought under 
the influence of the heat, which, volatilizing it, 
makes it traverse the ignited charcoal, where- 
by it is reduced. The metallic arsenic con- 
denses beyond the force of the spirit flame, in 
the shape of a dark metallic ring, which, by 
gently heating, can be driven further forward, 
and thus more is accumulated, by which it ac- 
quires a higher lustre. The small diameter of 
the tube prevents all circulation of air, so that 



ACID 



17 



ARSENIOUS. 



no part of the metal is oxidized. It now re- 
mains to determine the arsenic by its smell. 
This is effected if we cut the tube between the 
charcoal and the metal, then beat it gently in 
the place where the metal rests, while the nose 
is held over it at a little distance. 

When the poisoning has been caused by the 
solution of arsenic, or by the substance in fine 
powder, the contents of the stomach are to be 
heated, or even boiled with caustic potash, 
and then with muriatic acid. The filtered 
fluid is reduced by evaporation ; and, if ne- 
cessary, again filtered, and then subjected to 
a stream of sulphuretted hydrogen. The fluid 
is now heated to cause the precipitate to collect, 
or evaporated till it subsides. The sulphuret 
of arsenic is to be mixed with saltpetre, and 
deflagrated at the end of a hermetically sealed 
glass tube. A little saltpetre is first melted 
in the tube, and then small portions of the 
mixture are gradually dropped into it. The 
mass is to be dissolved in as few drops of water 
as possible ; then lime water is to be added in 
excess, and heated to boiling, by which the 
arseniate of lime is more easily collected and 
washed. The precipitate is collected, mixed 
with fresh-burned charcoal powder, and put 
into a glass tube, drawn out as above de- 
scribed, with its sealed end inflated into a 
very small bulb, in which the mixture is 
made to lie. The tube is first gently heated, 
to drive off any moisture the mixture may 
have absorbed, and then the under point of 
the bulb is kept in the flame of the blowpipe 
until the glass begins to melt. The arsenic 
is now reduced and collected in the neck of 
the bulb, where it is spread over so small a 
surface that the smallest quantity may be 
detected. In fact, one-tenth of a grain of 
sulphuret of arsenic is sufficient to afford a 
satisfactory and decisive reduction test. An- 
other mode of treating sulphuret of arsenic is, 
to introduce it into the narrow end of the 
tube first described, and to insert a piece of 
piano-forte wire (No. 11.), an inch in length, 
into the tube, so far as the surface of the sul- 
phuret. The steel wire is next to be heated 
in a spirit of wine lamp, and the heat gradu- 
ally raised in such a manner that the sulphu- 
ret, in the state of vapour, passes along the 
surface of the glowing iron. In this way, 
sulphuret of iron and sublimed metallic ar- 
senic are obtained. The operation ought to 
be conducted slowly. Iron turnings will not 
answer, because the arsenic combines with 
them without any sublimation. The garlic 
smell should never be trusted to without ac- 
tual reduction of the arsenic. 

For detecting the precise nature of the me- 
tallic crust of revived arsenic, when its quan- 
tity is too minute for its physical characters 
to be unequivocally ascertained, Dr Christison 
has added a very elegant test, which was sug- 
gested to him by Dr Turner. It consists in 
chasing the crust up and down the tube by 



heat, till all is oxidated ; when it assumes the 
form of sparkling crystals, which may be as- 
certained by a microscope of four powers to 
be octahedrons. 

It is to be observed, that one or two of the 
precipitation tests may be equivocal from ad- 
mixtures of various substances. Thus tinc- 
ture of ginger gives with the cupreous reagent 
a green precipitate ; and the writer of this ar- 
ticle was at first led to suspect from that ap- 
pearance, that an empirical tincture, put into 
his hands for examination, did contain arsenic. 
But a careful analysis satisfied him of its ge- 
nuineness. Tea covers arsenic from the cu- 
preous test. Such poisoned tea becomes by 
its addition of an obscure olive or violet red, 
but yields scarcely any precipitate. Sulphu- 
retted hydrogen, however, throws down from 
it a fine yellow sulphuret of arsenic. 

To remove the colouring matter of a ve- 
getable or animal kind, Mr Phillips has very 
properly recommended to mix the poisoned 
liquid with well washed animal charcoal 
(bone-black), and thereafter to filter, before 
applying the tests. 100 grains of black mix- 
ed with 500 of port wine, containing one 
grain of arsenious acid, became so decolour- 
ed as to admit of the application of tests. 

A good way of obviating all these sources 
of fallacy is to evaporate carefully to dryness, 
and expose the residue to heat in a glass tube. 
The arsenic sublimes, and may be afterwards 
operated on without ambiguity. M. Orfila 
has gone into ample details on the modifica- 
tions produced by wine, coffee, tea, broth, &c. 
on arsenical tests, of which a good tabular 
abstract is given in Mr Thomson's London 
Dispensatory. But it is evident that the dif- 
ferences in these menstrua, as also in beers, 
are so great as to render precipitations and 
changes of colour by reagents very unsatis- 
factory witnesses in a case of life and death. 
Hence the method of evaporation above de- 
scribed should never be neglected. Should 
the arsenic be combined with oil, the mixture 
ought to be boiled with water, and the oil 
then separated by the capillary action of wick- 
threads. If with resinous substances, these 
may be removed by oil of turpentine, not by 
alcohol (as directed by Dr Black), which is a 
good solvent of arsenious acid. It may more- 
over be observed, that both tea and coffee 
should be freed from their tannin by gelatin, 
which does not act on the arsenic previous to 
the use of reagents for the poison. When one 
part of arsenious acid in watery solution is 
added to ten parts of milk, the sulphuretted 
hydrogen present in the latter, occasions the 
white colour to pass into a canary yellow ; the 
cupreous test gives it a slight green tint, and 
the nitrate of silver produces no visible change, 
though even more arsenic be added ; but the 
hydrosulphurets throw down a golden yellow, 
with the aid of a few drops of an acid. The 
liquid contained in the stomach of a rabbit poi- 
B 



ACID 



II 



ARSENIOUS. 



soned with a solution of 3 grains of arsenious 
acid, afforded a white precipitate with nitrate 
of silver, greyish-white with lime water, green 
with the ammonia-sulphate, and deep yellow 
with sulphuretted hydrogen water. 

The preceding copious description of the 
habitudes of arsenious acid in different cir- 
cumstances, is equally applicable to the solu- 
ble arsenites. Their poisonous operation, as 
well as that of the arsenic acid, has been 
satisfactorily referred by Mr Brodie to the 
suspension of the functions of the heart and 
brain, occasioned by the absorption of these 
substances into the circulation, and their con- 
sequent determination to the nervous system 
and the alimentary canal. This proposition 
was established by numerous experiments on 
rabbits and dogs. Wounds were inflicted, 
and arsenic being applied to them, it was 
found that in a short time death supervened, 
with the same symptoms of inflammation of 
the stomach and bowels as if the poison had 
been swallowed. 

He divides the morbid affections into three 
classes : 1st, Those depending on the nervous 
system, as palsy at first of the posterior ex- 
tremities, and then of the rest of the body, 
convulsions, dilatation of the pupils, and ge- 
neral insensibility : 2d, Those which indicate 
disturbance in the organs of circulation ; for 
example, the feeble, slow, and intermitting 
pulse, weak contractions of the heart im- 
mediately after death, and the impossibility 
of prolonging them, as may be done in sudden 
deaths from other causes, by artificial re- 
spiration : 3d, Lastly, Those which depend 
on lesion of the alimentary canal, as the pains 
of the abdomen, nauseas, and vomitings, in 
those animals which were suffered to vomit. 
At one time it is the nervous system that is 
most remarkably affected, and at another the 
organs of circulation. Hence inflammation 
of the stomach and intestines ought not to be 
considered as the immediate cause of death, 
in the greater number of cases of poisoning 
by arsenic. However, should an animal not 
sink under the first violence of the poison, 
if the inflammation has had time to be de- 
veloped, there is no doubt that it may destroy 
life. Mr Earle states, that a woman who 
had taken arsenic resisted the alarming symp- 
toms which at first appeared, but died on the 
fourth day. On opening her body, the mu- 
cous membrane of the stomach and intestines 
was ulcerated to a great extent. Yet authen- 
tic cases of poison are recorded, where no 
trace of inflammation was perceptible in the 
primce vice. 

The effects of arsenic have been graphically 
represented by Dr Black : " The symptoms 
produced by a dangerous dose of arsenic begin 
to appear in a quarter of an hour, or not much 
longer, after it is taken. First sickness, and 
great distress at stomach, soon followed by 
thirst, and burning heat in the bowels. Then 



come on violent vomiting and severe colic 
pains, and excessive and painful purging. 
This brings on faintings with cold sweats, and 
other signs of great debility. To this succeed 
painful cramps and contractions of the legs 
and thighs, and extreme weakness, and death." ' 
Similar results have followed the incautious 
sprinkling of schirrous ulcers with powdered 
arsenic, or the application of arsenical pastes. 
The following more minute specification of 
symptoms is given by Orfila : " An austere 
taste in the mouth ; frequent ptyalism ; con- 
tinual spitting ; constriction of the pharynx 
and oesophagus ; teeth set on edge ; hiccups ; 
nausea ; vomiting of brown or bloody matter ; 
anxiety ; frequent fainting fits ; burning heat 
at the prcECordia ; inflammation of the lips, 
tongue, palate, throat, stomach ; acute pain 
of stomach, rendering the mildest drinks in- 
tolerable ; black stools of an indescribable 
fetor ; pulse frequent, oppressed, and irregu- 
lar sometimes slow and unequal ; palpita- 
tion of the heart ; syncope ; unextinguishable 
thirst; burning sensation over the whole 
body, resembling a consuming fire at times 
an icy coldness ; difficult respiration ; cold 
sweats ; scanty urine, of a red or bloody ap- 
pearance ; altered expression of countenance ; 
a livid circle round the eyelids ; swelling and 
itching of the whole body, which becomes 
covered with livid spots, or with a miliary 
eruption ; prostration of strength ; loss of 
feeling, especially in the feet and hands ; de- 
lirium, convulsions, sometimes accompanied 
with an insupportable priapism ; loss of the 
hair ; separation of the epidermis ; horrible 
convulsions ; and death." 

It is uncommon to observe all these fright- 
ful symptoms combined in one individual ; 
sometimes they are altogether wanting, as is 
shewn by the following case, related by M. 
Chaussier. A robust man of middle age swal- 
lowed arsenious acid in large fragments, and 
died without experiencing other symptoms 
than slight syncopes. On opening his sto- 
mach, it was found to contain the arsenious 
acid in the very same state in which he had 
swallowed it : There was no appearance what- 
ever of erosion or inflammation in the intes- 
tinal canal. Etmuller mentions a young girl's 
being poisoned by arsenic, and whose stomach 
and bowels were sound to all appearance, 
though the arsenic was found in them. In 
general, however, inflammation does extend 
along the whole canal, from the mouth to 
the rectum. The stomach and duodenum 
present frequently gangrenous points, eschars, 
perforations of all their coats ; the villous 
coat in particular, by this and all other cor- 
rosive poisons, is commonly detached, as if it 
were scraped off or reduced into a paste of a 
reddish-brown colour. From these considera- 
tions we may conclude, that from the exist- 
ence or non-existence of intestinal lesions, 
from the extent or seat of the symptoms alone, 



ACID 



BENZOIC. 



the physician should not venture to pronounce 
definitively on the fact of poisoning. 

The result of Mr Brodie's experiments on 
brutes teaches, that the inflammations of the 
intestines and stomach are more severe when 
the poison has been applied to an external 
wound, than when it has been thrown into the 
stomach itself. 

The best remedies against this poison in the 
stomach are copious draughts of bland liquids 
of a mucilaginous consistence, to inviscate 
the powder, so as to procure its complete 
ejection by vomiting. Sulphuretted hydrogen 
condensed in water is the only direct antidote 
to its virulence ; Orfila having found, that 
when dogs were made to swallow that liquid, 
after getting a poisonous dose of arsenic, they 
recovered, though their resophagus was tied 
to prevent vomiting ; but when the same dose 
of poison was administered in the same cir- 
cumstances, without the sulphuretted water, 
that it proved fatal. 

When the viscera are to be subjected after 
death to chemical investigation, a ligature 
ought to be thrown round the oesophagus and 
the beginning of the colon, and the interme- 
diate stomach and intestines removed. Their 
liquid contents should be emptied into a 
basin ; and thereafter a portion of hot water 
introduced into the stomach, and worked tho- 
roughly up and down this viscus, as well as 
the intestines. 

After filtration, a portion of the liquid 
should be concentrated by evaporation in a 
porcelain capsule, and then submitted to the 
proper reagents above described. We may 
also endeavour to extract from the stomach, 
by digestion in boiling water with a little 
ammonia, the arsenical impregnation, which 
has been sometimes known to adhere in mi- 
nute particles with wonderful obstinacy. This 
precaution ought therefore to be attended to. 
The heat will dissipate the excess of ammonia 
in the above operation ; whereas by adding 
potash of soda, as prescribed by the German 
chemists, we introduce animal matter in al- 
kaline solution, which complicates the inves- 
tigation. 

The matters rejected from the patient's 
bowels before death should not be neglected. 
These, generally speaking, are best treated 
by cautious evaporation to dryness ; but we 
must beware of heating the residuum to 
400, since at that temperature, and perhaps 
a little under it, the arsenious acid itself 
sublimes. 

Vinegar, hydroguretted alkaline sulphurets, 
and oils, are of no use as counterpoisons. 
Indeed, when the arsenic exists in substance 
in the stomach, even sulphuretted hydrogen 
water is of no avail, however effectually it 
neutralize an arsenious solution. Syrups, lin- 
seed tea, decoction of mallows, or tragacanth, 
and warm milk, should be administered as 
copiously as possible, and vomiting provoked 



by tickling the fauces with a feather. Clys- 
ters of a similar nature may be also employed. 
Many persons have escaped death by having 
taken the poison mixed with rich soups ; and 
it is well known, that when it is prescribed 
as a medicine, it acts most beneficially when 
given soon after a meal. These facts have 
led to the prescription of butter and oils ; the 
use of which is, however, not advisable, as 
they screen the arsenical particles from more 
proper menstrua, and even appear to aggravate 
its virulence. Morgagni, in his great work 
on the seats and causes of disease, states, that 
at an Italian feast the desert was purposely 
sprinkled over with arsenic instead of flour. 
Those of the guests who had previously ate 
and drank little, speedily perished ; those who 
had their stomachs well filled, were saved by 
vomiting. He also mentions the case of three 
children, who ate a vegetable soup poisoned 
with arsenic. One of them, who took only 
two spoonfuls, had no vomiting, and died ; 
the other two, who had eaten the rest, vo- 
mited, and got well. Should the poisoned 
patient be incapable of vomiting, a tube of 
caoutchouc, capable of being attached to a 
syringe, may be had recourse to. The tube 
and pump serve to introduce the drink, and 
to withdraw it after a few instants. 

It has been for some time known in Ger- 
many, that the bodies of persons poisoned with 
arsenic have been found, after several months, 
nay, two years and a half, in a state of re- 
markable preservation, or converted externally 
into a species of adipocerous matter ; and the 
stomach and intestines firm, flexible, reddish, 
as if they had been pickled in brine ; and the 
appearances of disease, caused by the arsenic, 
were often as distinct as in a recent body. 
Dr Christison has verified these results by ex- 
periments on dogs. Dr Kelch, of Konigsberg, 
buried, in February, the internal organs of a 
man who had died of arsenic, and whose body 
had remained without burial till the external 
parts had begun to decay ; and on examining 
the stomach and intestines, five months after- 
wards, he found that the hamper which con- 
tained them was very rotten, but that they had 
a peculiar smell, very different from that of 
putrid bowels, were not yet acted on by pu- 
trefaction, and were still as fresh as when they 
were taken from the body, and might have 
served to make instructive preparations. In 
the stomach, the inflamed spots seen origi- 
nally had not disappeared. In consequence 
of this preservation of the body, arsenic has 
been detected in Germany fourteen months 
after interment. This preservative power is, 
however, subject to exceptions, the causes of 
which have not been investigated. 

ACID (BENZOIC). The usual method 
of obtaining this acid affords a very elegant 
and pleasing example of the chemical process 
of sublimation. For this purpose a thin stra- 
tum of powdered benzoin is spread over the 



ACID 



20 



BENZOIC. 



bottom of a glazed earthen pot, to which a tall 
conical paper covering is fitted : gentle heat 
is then to be applied to the bottom of the pot, 
which fuses the benzoin, and fills the apart- 
ment with a fragrant smell, arising from a 
portion of essential oil and acid of benzoin 
which are dissipated into the air ; at the same 
time the acid itself rises very suddenly in the 
paper head, which may be occasionally in- 
spected at the top, though with some little 
care, because the fumes will excite coughing. 
This acid sublimate is condensed in the form 
of long needles, or straight filaments of a white 
colour, crossing each other in all directions. 
When the white acid ceases to rise, the cover 
may be changed, a new one applied, and the 
heat raised : more flowers of a yellowish colour 
will then rise, which require a second sub- 
limation to deprive them of the empyreumatic 
oil they contain. 

The sublimation of the acid of benzoin may 
be conveniently performed by substituting 
an inverted earthen pan instead of the paper 
cone. In this case the two pans should be 
made to fit, by grinding on a stone with sand, 
and they must be luted together with paper 
dipped in paste. This method seems pre- 
ferable to the other, w here the presence of the 
operator is required elsewhere ; but the paper 
head can be more easily inspected and chang- 
ed. The heat applied must be very gentle, 
and the vessels ought not to be separated till 
they have become cool. 

The quantity of acid obtained by these 
methods differs according to the management, 
and probably also from difference of purity, 
and in other respects, of the balsam itself. 
It usually amounts to no more than about 
one-eighth part of the whole weight. Indeed 
Scheele says, not more than a tenth or twelfth. 
The whole acid of benzoin is obtained with 
greater certainty in the humid process of 
Scheele : this consists in boiling the powdered 
balsam with lime and water, and afterwards 
separating the lime by the addition of muria- 
tic acid. Twelve ounces of water are to be 
poured upon four ounces of slaked lime ; and 
after the ebullition is over, eight pounds, or 
ninety-six ounces, more of water are to be 
added : a pound of finely powdered benzoin 
being then put into a tin vessel, six ounces of 
the milk of lime are to be added, and mixed 
well with the powder ; and afterwards the rest 
of the lime water in the same gradual manner, 
because the benzoin would coagulate into a 
mass, if the whole were added at once. This 
mixture must be gently boiled for half an 
hour with constant agitation, and afterwards 
suffered to cool and subside during an hour. 
The supernatant liquor must be decanted, 
and the residuum boiled with eight pounds 
more of lime water ; after which the same 
process is to be once more repeated : the re- 
maining powder must be edulcorated on the 
filter by affusions of hot water. Lastly, all 



the decoctions, being mixed together, must be 
evaporated to two pounds, and strained into 
a glass vessel. 

This fluid consists of the acid of benzoin 
combined with lime. After it is become 
cold, a quantity of muriatic acid must be 
added, with constant stirring, until the fluid 
tastes a little sourish. During this time the 
last-mentioned acid unites with the lime, and 
forms a soluble salt, which remains suspend- 
ed, while the less soluble acid of benzoin, 
being disengaged, falls to the bottom in 
powder. By repeated affusions of cold water 
upon the filter, it may be deprived of the 
muriate of lime and muriatic acid with which 
it may happen to be mixed. If it be requir- 
ed to have a shining appearance, it may be 
dissolved in a small quantity of boiling water, 
from which it will separate in silky filaments 
by cooling. By this process the benzoic acid 
may be procured from other substances in 
which it exists. 

Mr Hatchett has shewn, that, by digesting 
benzoin in hot sulphuric acid, very beautiful 
crystals are sublimed. This is perhaps the 
best process for extracting the acid. If we 
concentrate the urine of horses or cows, and 
pour muriatic acid into it, a copious precipi- 
tate of benzoic acid takes place. This is the 
cheapest source of it. 

Benzoic acid has been found by M. Vogel 
in the sweet-scented vernal grass (anthoxan- 
thum odoratum), and in the sweet-scented 
soft grass (holcus odoratus); two grasses 
which communicate to hay their peculiar 
aroma. 

The acid of benzoin is so inflammable, 
that it burns with a clear yellow flame with- 
out the assistance of a wick. The sublimed 
flowers in their purest state, as white as or- 
dinary writing paper, were fused into a clear 
transparent yellowish fluid, at the two hun- 
dred and thirtieth degree of Fahrenheit's 
thermometer, and at the same time began 
to rise in sublimation. It is probable that 
a heat somewhat greater than this may be 
required to separate it from the resin. It is 
strongly disposed to take the crystalline form 
in cooling. The concentrated sulphuric and 
nitric acids dissolve this concrete acid ; and 
it is again separated, without alteration, by 
adding water. Other acids dissolve it by the 
assistance of heat, from which it separates by 
cooling, unchanged. It is plentifully solu- 
ble in ardent spirit, from which it may like- 
wise be separated by diluting the spirit with 
water. It readily dissolves in oils, and in 
melted tallow. If it be added in a small 
proportion to this last fluid, part of the tal- 
low congeals before the rest, in the form of 
white opaque clouds. If the quantity of acid 
be more considerable, it separates in part by 
cooling, in the form of needles or feathers. 
In the destructive distillation of tallow, ben- 
zoic acid is said to be formed. 



ACID 



21 



BORACIC. 



At the temperature of boiling water, oil of 
turpentine dissolves about its own weight of 
benzoic acid, but the solution becomes con- 
crete on cooling. 

Pure benzoic acid is in the form of a light 
powder, evidently crystallized in fine needles, 
the figure of which is difficult to be deter- 
mined from their smallness. It has a white 
and shining appearance ; but when contami- 
nated by a portion of volatile oil, is yellow 
or brownish. It is not brittle, as might be 
expected from its appearance, but has rather 
a kind of ductility and elasticity, and, on 
rubbing in a mortar, becomes a sort of paste. 
Its taste is acrid, hot, acidulous, and bitter. 
It reddens the infusion of litmus, but not 
syrup of violets. It has a peculiar aromatic 
smell, but not strong unless heated. This, 
however, appears not to belong to the acid ; 
for M. Giese informs us, that on dissolving 
the benzoic acid in as little alcohol as possi- 
ble, filtering the solution, and precipitating by 
water, the acid will be obtained pure, and void 
of smell, the odorous oil remaining dissolved 
in the spirit. Its specific gravity is 0.667. It 
is not perceptibly altered by the air, and has 
been kept in an open vessel twenty years with- 
out losing any of its weight. None of the 
combustible substances have any effect on it ; 
but it may be refined by mixing it with char- 
coal powder and subliming, being thus ren- 
dered much whiter and better crystallized. It 
is not very soluble in water. Wenzel and 
Lichtenstein say four hundred parts of cold 
water dissolve but one, though the same 
quantity of boiling water dissolves twenty 
parts, nineteen of which separate on cooling. 

Berzelius states the composition of benzoic 
acid to be, carbon 74.41, oxygen 20.43, and 
hydrogen 5.16, in 100. From the benzoate 
of lead, he deduces the prime equivalent to 
be 14.893. By my experiments its compo- 
nents are, carbon 66.74, oxygen 28.32, and 
hydrogen 4.94; and by saturation with am- 
monia its prime equivalent appeared to be 
14.5, to oxygen 1. 

The benzoic acid unites without much 
difficulty with the earthy and alkaline bases. 

The benzoate of baryta is soluble, and 
crystallizes. That of lime is very soluble in 
water, though much less in cold than in hot, 
and crystallizes on cooling. The benzoate of 
magnesia is soluble, crystallizable, and a little 
deliquescent. That of alumina is very soluble, 
crystallizes in dendrites, is deliquescent, and 
has an acerb and bitter taste. The benzoate 
of potash crystallizes on cooling in little com- 
pacted needles. The benzoate of soda is very 
crystallizable, very soluble, and not deliques- 
cent like that of potash, but it is decomposable 
by the same means. It is sometimes found 
native in the urine of graminivorous qua- 
drupeds, but by no means so abundantly as 
that of lime. The benzoate of ammonia is 
volatile, and decomposable by all the acids 



and all the bases. The solutions of all the 
benzoates, when drying on the sides of a ves- 
sel wetted with them, form dendritical crystal- 
lizations. 

TrommsdorfF found in his experiments, 
that benzoic acid united readily with metallic 
oxides. 

The benzoates are all decomposable by 
heat, which, when it is slowly applied, first 
separates a portion of the acid in a vapour 
that condenses in crystals. The soluble ben- 
zoates are decomposed by the powerful acids, 
which separate their acid in a crystalline form. 
The benzoate of ammonia has been proposed 
by Berzelius as a reagent for precipitating 
red oxide of iron from perfectly neutral solu- 
tions. See SALTS (TABLE OF). 

ACID (BOLETIC). An acid extracted 
from the expressed juice of the boletus pseudo- 
igniarius by M. Braconnot. This juice, con- 
centrated to a syrup by a very gentle heat, 
was acted on by strong alcohol. What re- 
mained was dissolved in water. When ni- 
trate of lead was dropped into this solution, 
a white precipitate fell, which, after being 
well washed with water, was decomposed by 
a current of sulphuretted hydrogen gas. Two 
different acids were found in the liquid after 
filtration and evaporation. One in perma- 
nent crystals was BOLETIC acid; the other 
was a small proportion of phosphoric acid. 
The former was purified by solution in alco- 
hol, and subsequent evaporation. 

It consists of irregular four-sided prisms, 
of a white colour, and permanent in the air. 
Its taste resembles cream of tartar. At the 
temperature of 68 it dissolves in 180 times 
its weight of water, and in 45 of alcohol. 
Vegetable blues are reddened by it. Red 
oxide of iron, and the oxides of silver and 
mercury, are precipitated by it from their 
solutions in nitric acid ; but lime and baryta 
waters are not affected. It sublimes when 
heated in white vapours, and is condensed in 
a white powder Ann. de Chimie, Ixxx. 

ACID (BOMBIC). An acid which M. 
Chaussier extracted from the silk worm in 
1781. 

ACID (BORACIC). The salt composed 
of this acid and soda had long been used, both 
in medicine and the arts, under the name of 
borax, when Homberg first obtained the acid 
separate in 1702, by distilling a mixture of 
borax and sulphate of iron. Lemery the 
younger soon after discovered that it could be 
obtained from borax equally by means of the 
nitric or muriatic acid. Geoffroy detected 
soda in borax ; and at length Baron proved 
by a number of experiments, that borax is a 
compound of soda and a peculiar acid. 

To procure the acid, dissolve borax in hot 
water, and filter the solution ; then add sul- 
phuric acid, by little and little, till the liquid 
has a sensibly acid taste. Lay it aside to 
cool, and a great number of small shining 



ACID 



22 



13ORACIC. 



laminated crystals will form. These are the 
boracic acid. They are to be washed with 
cold water, and drained upon paper. 

Boracic acid thus procured is in the form 
of thin irregular hexagonal scales, of a silvery 
whiteness, having some resemblance to sper- 
maceti, and the same kind of greasy feel. It 
has a sourish taste at first, then makes a bit- 
terish cooling impression, and at last leaves 
an agreeable sweetness. Pressed between 
the teeth, it is not brittle but ductile. It has 
no smell ; but when sulphuric acid is poured 
on it, a transient odour of musk is produced. 
Its specific gravity in the form of scales is 
1.479; after it has been fused, 1.803. It is 
not altered by light. Exposed to the fire, it 
swells up, from losing its water of crystal- 
lization, and in this state is called calcined 
boracic acid. It melts a little before it is 
red-hot, without perceptibly losing any water ; 
but it does not flow freely till it is red, and 
then less than the borate of soda. After this 
fusion it is a hard transparent glass, becom- 
ing a little opaque on exposure to the air, 
without abstracting moisture from it, and un- 
altered in its properties ; for on being dis- 
solved in boiling water it crystallizes as be- 
fore. This glass is used in the composition 
of false gems. 

Boiling water scarcely dissolves one-fiftieth 
part, and cold water much less. When this 
solution is distilled in close vessels, part of 
the acid rises with the water, and crystallizes 
in the receiver. It is more soluble in alcohol ; 
and alcohol containing it burns with a green 
flame, as does paper dipped in a solution of 
boracic acid. 

Crystallized boracic acid is a compound of 
57 parts of acid and 43 of water. The honour 
of discovering the radical of boracic acid is 
divided between Sir H. Davy and MM. Gay 
Lussac and Thenard. The first, on applying 
his powerful voltaic battery to it, obtained a 
chocolate-coloured body in small quantity ; 
but the two latter chemists, by acting on it 
and potassium in equal quantities, at a low red 
heat, formed boron and sub-borate of potash. 
For a small experiment, a glass tube will serve, 
but on a greater scale a copper tube is to be 
preferred. The potassium and boracic acid, 
perfectly dry, should be intimately mixed 
before exposing them to heat. On withdraw- 
ing the tube from the fire, allowing it to cool, 
and removing the cork which loosely closed its 
mouth, we then pour successive portions of 
water into it, till we detach or dissolve the 
whole matter. The water ought to be heated 
each time. The whole collected liquids are 
allowed to settle ; when, after washing the 
precipitate till the liquid ceases to affect syrup 
of violets, we dry the boron in a capsule, and 
then put it into a phial out of contact of air. 
Boron is solid, tasteless, inodorous, and of a 
greenish-brown colour. Its specific gravity 
is somewhat greater than water. 



The prime equivalent of boracic acid has 
been inferred, from the borate of ammonia, to 
be about 2.7 or 2.8 ; oxygen being 1 .0 ; and 
it probably consists of 2.0 of oxygen -|- 0.8 
of boron. But by MM. Gay Lussac and 
Thenard, the proportions would be 2 of bo- 
ron to 1 of oxygen. 

Boracic acid has a more powerful attraction 
for lime than for any other of the bases, 
though it does not readily form borate of lime 
by adding a solution of it to lime water, or 
decomposing by lime water the soluble alka- 
line borates. In either case an insipid white 
powder, nearly insoluble, which is the borate 
of lime, is however precipitated. The borate 
of baryta is likewise an insoluble, tasteless, 
white powder. 

One of the best known combinations of this 
acid is the native magnesia-borate of Kalk- 
berg, near Lunenburg. See BORACITE. 

The borate of potash is but little known. 

With soda the boracic acid forms a salt of 
considerable use in the arts, and long known 
by the name of borax. 

M. Payen has lately described a variety of 
borax which crystallizes in regular octahe- 
drons, is harder than common borax, and is 
almost as sonorous as cast-iron. Its fracture 
is vitreous, and rather undulated. It differs 
little from common borax, except in contain- 
ing less water of crystallization, and is there- 
fore preferred in Paris for soldering copper. 
It is prepared by subjecting solution of com- 
mon borax to ebullition, and then allowing it 
to cool and crystallize. Borax is to be dis- 
solved in water at 212 Fahr. in such quan- 
tity as to give a solution of specific gravity 
1.246. When left to cool slowly and regu- 
larly, small octahedral crystals begin to form 
at the temperature of 174 F., which increase 
in number and size till the temperature is 
133. If the mother liquor be now decant- 
ed, all the crystals left are of the kind before 
described ; but nearly all the crystals formed 
under this heat are borax of the ordinary 
sort. If the density of the boiling solution be 
no higher than 1.170, only common crystals 
are obtained. Thus the one or other kind 
may be obtained at pleasure. 

According to M. Arfwedson, borax con- 
sists, in the dry or calcined state, of acid 68.9, 
soda 31.1, in 100. It was analyzed by mix- 
ing it with three or four times its weight of 
finely powdered fluor-spar, free from silica, 
and a sufficient quantity of sulphuric acid. 
On evaporating the mixture, and exposing it 
to a red heat, all the boracic acid was expelled 
as fluoboric acid gas, and from the resulting 
sulphate of soda the quantity of this alkaline 
base was inferred. 

Gmelin found borax to contain in the crys- 
tallized state 46.6 per cent of water ; and in 
the dry state he regards it as a compound of 
two parts by weight of acid and one of base. 
Borax, therefore, instead of being called, as 



ACID 



23 



BUTYRIC. 



heretofore, the sub-borate of soda, should be 
viewed as a bi-borate. 

From M. Arfwedson's analysis the prime 
equivalent of boracic acid would seem to be 
4.4, and from M. Gmelin's 4. Dr Thomson 
makes it only 3. More recently M. Soubei- 
rons finds borax to consist of acid 67.584, 
base 32.416 ; whence the equivalent of bora- 
cic acid comes out 4. 1 75. 

M. Payen found 100 parts of prismatic 
borax to contain 46.95 of water ; and 100 of 
the octahedral 30. 64 of water. He gives the 
constitution of these salts as follows : 

Anhyd. Bor. Prism. Bor. Octahed. Bor. 
Atoms. Atoms. Atoms. 

Bor. ac. 2 = 88 2= 88 2=88 
Soda, 1 = 39.09 1= 39.09 1 = 39.09 

Water, 10=112.43 5 = 56.217 

127.09 239.52 183.307 

Borate of ammonia forms in small rhom- 
boidal crystals, easiiy decomposed by fire ; or 
in scales, of a pungent urinous taste, which 
lose the crystalline form, and grow brown on 
exposure to the air. 

Borate of baryta, when melted, and then 
cut and polished, exhibits a high degree of 
lustre, and closely resembles the topaz of 
Saxony. 

Boracic acid unites with silex by fusion, 
and forms with it a solid and permanent vi- 
treous compound. 

Boracic acid has been found in a disengag- 
ed state in several lakes of hot mineral waters 
near Monte Rotondo, Berchiaio, and Cas- 
tellonuovo in Tuscany, in the proportion of 
nearly nine grains in a hundred of water, by 
M. Hoeffer. M. Mascagni also found it ad- 
hering to schistus, on the borders of lakes, of 
an obscure white, yellow, or greenish colour, 
and crystallized in the form of needles. He 
has likewise found it in combination with am- 
monia. See SALT. 

ACID (BROMIC). When bromeis agi- 
tated with a sufficiently concentrated solution 
of potash, two very different compounds are 
formed. Hydrobromate of potash remains 
dissolved in the liquid. A white powder pre- 
cipitates to the bottom of the vessel, of a crys- 
talline aspect, which fuses on red-hot coals 
like nitre, and is transformed by heat into 
bromide of potassium, with the disengage- 
ment of oxygen. This crystalline powder is 
bromate of potash. It is scarcely soluble in 
alcohol, but in boiling water it dissolves pretty 
copiously ; from which solution, by cooling, 
there fall down needles grouped together. 
When crystallized by evaporation, the bro- 
mate is deposited in crystalline plates, with 
little lustre. It deflagrates on ignited char- 
coal ; and, when mixed in powder with sub- 
limed sulphur, it detonates on being struck 
by a hammer. 

The solution of this salt yields a precipitate 
with nitrate of silver. This white and pul- 
verulent precipitate, blackening with diffi- 



culty on contact with light, is thereby dis- 
tinguished from bromide of silver, which is 
yellowish, curdy, and easily affected by the 
sunbeams. 

The salts of lead, which produce an abun- 
dant crystalline precipitate with hydrobromate 
of potash, have no effect on the bromate. 

Bromate of baryta forms acicular crystals, 
soluble in boiling water, scarcely so in cold 
water, and melting with a green flame on 
burning coals. 

On pouring dilute sulphuric acid into the 
solution of bromate of baryta, so as to preci- 
pitate the whole of the base, a dilute solution 
of bromic acid is obtained. The bromate of 
baryta is best obtained for this purpose by 
combining chlorine with brome, and by plac- 
ing this compound in contact with a solution 
of that earth. 

By slow evaporation the greater part of the 
water may be removed. It then acquires a 
syrupy consistence. If the temperature be 
raised higher with the view of expelling the 
water completely, one portion of the acid eva- 
porates, and the other is decomposed into 
oxygen and brome. The same change seems 
to ensue when the concentration is pushed 
too far by the action of a surface of sulphuric 
acid in vacuo. Water thus appears to be ne- 
cessary to the constitution of bromic acid. 

This acid first reddens litmus paper, and 
soon thereafter deprives it of colour. It has 
scarcely any smell. Its taste is very acid, but 
not at all corrosive. 

The hydracids, as also those which are not 
saturated with oxygen, act with great energy 
on bromic acid. The sulphurous, muriatic, 
hydriodic, and hydrobromic acids decompose 
it, as well as sulphuretted hydrogen. From 
hydriodic acid, compounds of brome with 
chlorine and iodine result. 

Bromic acid appears to be composed, in 
100 parts, of 64.69 brome, 
35.31 oxygen. 

If it contain, like the chloric acid, 5 atoms of 
oxygen, the atomic weight of brome would 
thus be 9. 1 ; but other experiments seem to 
make it 9.5 ; whence the acid should consist 
of 65.52 brome -f- 34.48 oxygen. 

ACID (OF THE BUG). This acid is 
merely mentioned by Thenard, as a peculiar 
compound. 

ACID (BUTYRIC). We owe the dis- 
covery of this acid to M. Chevreul. Butter, 
he says, is composed of two fat bodies, ana- 
logous to those of hog's lard, of a colouring 
principle, and a remarkably odorous one, to 
which it owes the properties that distinguish 
it from the fats, properly so called. This 
principle, which he has called butyric acid, 
forms well characterized salts with baryta, 
strontia, lime, the oxides of copper, lead, 
&c. ; 100 parts of it neutralize a quantity of 
base which contains about ten of oxygen. M. 
Chevreul has not explained his method of 



ACID 



24 



CARBAZOTIC. 



separating this acid from the other consti- 
tuents of butter See Journ. de Pharmacie, 
iii. 80. 

ACID (CAMPHORIC). One part of 
camphor being introduced into a glass retort, 
four parts of nitric acid, sp. gr. 1.33, are to be 
poured on it, a receiver adapted to the retort, 
and all the joints well luted. The retort is 
then to be placed on a sand heat, and gradu- 
ally heated. During the process a consider- 
able quantity of nitrous gas, and of carbonic 
acid gas, is evolved ; and part of the camphor 
is volatilized, while another part seizes the 
oxygen of the nitric acid. When no more 
vapours are extricated, the vessels are to be 
separated, and the sublimed camphor added 
to the acid that remains in the retort. A like 
quantity of nitric acid is again to be poured 
on this, and the distillation repeated. This 
operation must be repeated till the camphor 
is completely acidified. Twenty parts of 
nitric acid is sufficient to acidify one of 
camphor. 

When the whole of the camphor is acidified, 
it crystallizes in the remaining liquor. The 
whole is then to be poured out upon a filter, 
and washed with distilled water, to carry off 
the nitric acid it may have retained. The 
most certain indication of the acidification of 
the camphor is its crystallizing on the cooling 
of the liquor remaining in the retort. 

To purify this acid it must be dissolved in 
hot distilled water, and the solution, after 
being filtered, evaporated nearly to half, or 
till a slight pellicle forms ; when the cam- 
phoric acid will be obtained in crystals on 
cooling. 

Camphoric acid has a slightly acid bitter 
taste, and reddens infusion of litmus. 

It crystallizes ; and the crystals upon the 
whole resemble those of muriate of ammonia. 
It effloresces on exposure to the atmosphere ; 
is not very soluble in cold water ; when placed 
on burning coals, it gives out a thick aromatic 
smoke, and is entirely dissipated ; and with a 
gentle heat melts, and is sublimed. It is so- 
luble in alcohol, and is not precipitated from 
it by water ; a property that distinguishes it 
from the benzoic acid. It unites easily with 
the earths and alkalis. See SALTS (TABLE 
OF). 

ACID (CAPRI C). An acid obtained by 
Chevreul from the soap made with the butter 
of cow's milk, and so named because it has a 
smell like that of a goat. At 5 Fahr. it 
exists in the form of crystals. At 65 F. its 
sp. gr. is 0.910 : 100 parts water dissolve only 
0.12, but with alcohol it combines in all pro- 
portions. 

ACID (CAPROIC). An acid similar 
to the preceding, and obtained from the same 
source. 

Its prime equivalent in the crystalline state 
seems to be about 1 1. 

ACID (CARBAZOTIC). To obtain 



pure carbazotic acid, says M. Liebeg its dis- 
coverer, the finest indigo is to be crushed and 
heated moderately, with eight or ten times its 
weight of nitric acid : it dissolves with effer- 
vescence, and produces much nitrous vapour. 
When the scum has fallen, it is to be boiled, 
and fresh acid added, until no more nitrous 
vapour be exhaled ; in which case neither 
resin nor artificial tannin is produced. When 
the liquid cools, hard, yellow, transparent 
crystals form, which are to be taken out and 
washed. They are to be dissolved in boiling 
water, and the few drops of oleaginous liquid 
on the surface are to be removed with bibu- 
lous paper. By filtration and cooling a large 
quantity of brilliant yellow lamellar crystals 
are obtained. These are to be then dissolved 
in boiling water, and saturated with carbonate 
of potash, so as to obtain the carbazotate of 
this base by cooling the liquor. This salt 
must be purified by repeated crystallizations. 
Its solution will then afford, with sulphuric, 
nitric, or muriatic acid, brilliant, clear, yellow 
crystals in plates, mostly triangular, which 
are the pure acid. Four parts of the best 
indigo yield one of carbazotic acid. 

The carbazotate of lead is readily formed 
from the pure acid and carbonate of lead. 
It is a yellow powder, scarcely soluble in 
water, and, when dry, detonating strongly by 
heat or percussion. It has indeed been pro- 
posed for the discharge of percussion guns. 
Carbazotate of copper crystallizes in long 
rhombic needles of an emerald-green colour ; 
which are soluble in water, and in air efflo- 
resce, becoming yellow. 

The composition of carbazotic acid is thus 
given by M. Liebeg : 

Carbon, 35.043 

Azote, 16.167 

Oxygen, 48.790 

100.000 

Carbazotate of mercury is a compound of 
53.79 acid -j- 46.21 protoxide of the metal. 

Carbazotic acid is but slightly soluble in 
cold, but much more so in boiling water ; and 
the solution has a bright yellow colour, red- 
dens litmus, has an extremely bitter taste, 
and acts like a strong acid on metallic oxides, 
dissolving them, and forming peculiar salts. 
Ether and alcohol dissolve the acid readily. 

When fused in contact with chlorine or 
iodine, it is not decomposed, nor does solu- 
tion of chlorine affect it. Cold sulphuric acid 
has no action on it; hot dissolves it; but 
water separates the substance without altera- 
tion. Boiling muriatic acid does not affect 
it ; and nitro- muriatic acid only with great 
difficulty. These results shew that no nitric 
acid is present in it. 

Carbazotate of potash crystallizes in long 
yellow quadrilateral needles, semitransparent 
and very brilliant : it dissolves in 260 parts of 
water at 59 F., and in much less of boiling 



ACID 



CARBONIC. 



water ; indeed, a saturated boiling hot solution 
becomes on cooling a yellow mass of needles, 
from which scarcely any fluid will run. 
When a little is gradually heated in a glass 
tube, it first fuses, and then suddenly explodes, 
breaking the tube to fragments, in which traces 
of charcoal are observable. The slight solu- 
bility of this salt offers an easy method of test- 
ing and separating potash in a fluid. The 
saturated solution of salt at 59 F. is not dis- 
turbed by muriate of platinum. It contains 
no water of crystallization. Its constituents 
are, Carbazotic acide, 83.79 
Potash, 16.21 

100.00 

Carbazotate of soda crystallizes in fine silky 
yellow needles, having the general properties 
of the salt of potash, but soluble in from 20 
to 24 parts of water at 60 F. 

Carbazotate of ammonia forms very long, 
flattened, brilliant, yellow crystals, very soluble 
in water. Carbazotate of baryta is obtained 
by heating the carbonate of this earth in dilute 
carbazotic acid. It crystallizes in quadran- 
gular prisms of a deep colour, which dissolve 
easily in water. When heated it fuses, and is 
decomposed with very powerful explosion, ac- 
companied with a vivid yellow flame. The 
explosion resembles that of fulminating silver. 
1 00 parts of the crystallized barytic salt consist 
of acid 69.16, baryta 21.60, and water 9.24. 

Carbazotate of lime, obtained like that of 
baryta, is in flattened quadrangular prisms, 
very soluble in water, and detonating like the 
salt of potash. 

Carbazotate of silver is made by dissolving 
the oxide of the metal in the hot dilute acid ; 
and on gradual evaporation of the liquid, starry 
groups of fine acicular crystals, of the colour 
and lustre of gold, are obtained. The salt is 
readily soluble in water. When heated to a 
certain degree, it does not detonate, but fuses. 

ACID (CARBONIC). This acid, being 
a compound of carbon and oxygen, may be 
formed by burning charcoal ; but as it exists 
in great abundance ready formed, it is not ne- 
cessary to have recourse to this expedient. All 
that is necessary is to pour sulphuric or mu- 
riatic acid, diluted with five or six times its 
weight of water, on common chalk, which is a 
compound of carbonic acid and lime. An 
effervescence ensues ; carbonic acid is evolved 
in the state of gas, and may be received in 
the usual manner. 

Carbonic acid abounds in great quantities 
in nature, and appears to be produced in a 
variety of circumstances. It composes T 4 5 4 S of 
the weight of limestone, marble, calcareous 
spar, and other natural specimens of calcareous 
earth, from which it may be extricated either 
by the simple application of heat, or by the 
superior affinity of some other acid ; most acids 
having a stronger action on bases than this. 
Water, under the common pressure of the 



atmosphere, and at a low temperature, absorbs 
somewhat more than its bulk of fixed air, and 
then appears acidulous. If the pressure be 
greater, the absorption is augmented. It is 
to be observed, likewise, that more gas than 
the water will absorb, should be present. 
Heated water absorbs less ; and if water im- 
pregnated with this acid be exposed on a brisk 
fire, the rapid escape of the aerial bubbles 
affords an appearance as if the water were at 
the point of boiling, when the heat is not 
greater than the hand can bear. Congelation 
separates it readily and completely from wa- 
ter ; but no degree of cold simply has yet 
brought this acid to a state of fluidity. 

Carbonic acid is denser than common air, 
iu the proportion of 1.5277 to 1.0000; and for 
this reason occupies the lower parts of such 
mines or caverns as contain materials which 
afford it by decomposition. The miners call 
it choke-damp. The Grotto del Cano, in the 
kingdom of Naples, has been famous for ages 
on account of the effects of a stratum of fixed 
air which covers its bottom. It is a cave or 
hole in the side of a mountain, near the lake 
Agnano, measuring not more than eighteen 
feet from its entrance to the inner extremity; 
where if a dog or other animal that holds down 
its head be thrust in, it is immediately killed 
by inhaling this noxious fluid. 

Carbonic acid gas is emitted in large quan- 
tities by bodies in the state of the vinous 
fermentation, (see FERMENTATION) ; and, on 
account of its great weight, it occupies the 
apparently empty space or upper part of the 
vessels in which the fermenting process is 
going on. A variety of striking experiments 
may be made in this stratum of elastic fluid. 
Lighted paper, or a candle dipped into it, is 
immediately extinguished ; and the smoke re- 
maining in the carbonic acid gas renders its 
surface visible, which may be thrown into 
waves by agitation like water. If a dish of 
water be immersed in this gas, and briskly 
agitated, it soon becomes impregnated, and 
obtains the pungent taste of Pyrmont water. 
In consequence of the weight of the carbonic 
acid gas, it may be lifted out in a pitcher or 
bottle, which, if well corked, may be used to 
convey it to great distances, or it may be drawn 
out of a vessel by a cock like a liquid. The 
effects produced by pouring this invisible fluid 
from one vessel to another, have a very sin- 
gular appearance : if a candle or small animal 
be placed in a deep vessel, the former becomes 
extinct, and the latter expires in a few seconds, 
after the carbonic acid gas is poured upon 
them, though the eye is incapable of distin- 
guishing any thing that is poured. If, how- 
ever, it be poured into a vessel full of air, in 
the sunshine, its density, being so much 
greater than that of the air, renders it slightly 
visible by the undulations and streaks it forms 
in this fluid, as it descends through it. 

Carbonic acid reddens infusion of litmus; 



ACID 



26 



CARBONIC. 



but the redness vanishes by exposure to the 
air, as the acid flies off. It has a peculiar sharp 
taste, which may be perceived over vats in 
which wine or beer is fermenting, as also in 
sparkling Champaign, and the brisker kinds 
of cider. It consists, in 100 parts, of oxygen 
72.72, the other 27.28 being pure carbon. 
It not only destroys life, but the heart and 
muscles of animals killed by it lose all their 
irritability, so as to be insensible to the stimu- 
lus of galvanism. 

Carbonic acid is dilated by heat, but not 
otherwise altered by it. It is not acted upon 
by oxygen. Charcoal absorbs it, but gives it 
out again unchanged, at ordinary tempera- 
tures ; but when this gaseous acid is made to 
traverse charcoal ignited in a tube, it is con- 
verted into carbonic oxide. Phosphorus is 
insoluble in carbonic acid gas ; but is capable 
of decomposing it by compound affinity, when 
assisted by sufficient heat ; and Priestley and 
Cruickshank have shewn, that iron, zinc, and 
several other metals, are capable of producing 
the same effect. 

Carbonic acid appears from various experi- 
ments of Ingenhousz to be of considerable 
utility in promoting vegetation. It is pro- 
bably decomposed by the organs of plants, its 
base furnishing part at least of the carbon that 
is so abundant in the vegetable kingdom, and 
its oxygen contributing to replenish the at- 
mosphere with that necessary support of life, 
which is continually diminished by the res- 
piration of animals and other causes. 

The most exact experiments on the neutral 
carbonates concur to prove, that the prime 
equivalent of carbonic acid is 2.75 ; and that 
it consists of one prime of carbon = 0.75 -f- 
2.0 oxygen. This proportion is most exactly 
deduced from a comparison of the specific 
gravities of carbonic acid gas and oxygen ; 
for it is well ascertained, that the latter, by its 
combination with charcoal, and conversion in- 
to the former, does not change its volume. 
Now, 100 cubic inches of oxygen weigh 33.8 
gr. and 100 cubic inches of carbonic acid 
46.5, showing the weight of combined char- 
coal in that quantity to be 12.7. But the 
oxide of carbon contains only half the quantity 
of oxygen which carbonic acid does ; and we 
hence infer, that the oxide of carbon consists 
of one prime of oxygen united to one of car- 
bon. This a priori judgment is confirmed by 
the weight 2.75 deduced from the carbonates, 
as the prime equivalent of carbonic acid. 
Therefore we have this proportion : 

If 33.8 represent two primes of oxygen or 
2 ; 1 2.7 will represent one of carbon ; 33.8 : 
2 : : 12.7: 0.751, being, as above, the prime 
equivalent or first combining proportion of 
carbon. If the specific gravity of atmospheric 
air be called 1.0000, that of carbonic acid 
will be 1.5277, as above stated. 

We have seen that water absorbs about its 
volume of this acid gas, and thereby acquires 



a specific gravity of 1.0015. On freezing it, 
the gas is as completely expelled as by boiling. 
By artificial pressure with forcing pumps, 
water may be made to absorb two or three 
times its bulk of carbonic acid. When there 
is also added a little potash or soda, it be- 
comes aerated or carbonated alkaline water ; 
a pleasant beverage, and a not inactive remedy 
in several complaints, particularly dyspepsia, 
hiccup, and disorders of the kidneys. Alcohol 
condenses twice its volume of carbonic acid. 
The most beautiful analytical experiment with 
carbonic acid is the combustion of potassium 
in it, the formation of potash, and the depo- 
sition of charcoal. Nothing shows the power 
of chemical research in a more favourable 
light than the extraction of an invisible gas 
from Parian marble or crystallized spar, and 
its resolution by such an experiment into 
oxygen and carbon. From the proportions 
above stated, 5 gr. of potassium should be 
used for 3 cubic inches of gas. If less be 
employed, the whole gas will not be decom- 
posed, but a part will be absorbed by the pot- 
ash. From the above quantities 3-8ths of a 
grain of charcoal will be obtained. If a por- 
celain tube, containing a coil of fine iron wire, 
be ignited in a furnace, and if carbonic acid 
be passed .backwards and forwards by means 
of a full and empty bladder attached to the 
ends of the tube, the gas will be converted into 
carbonic oxide, and the iron will be oxidized. 

Carbonic acid gas may be rendered liquid 
by great pressure. Take a strong glass syphon, 
and seal the end of its shorter leg. By means 
of a long glass funnel, nearly fill that leg with 
strong sulphuric acid : obstruct the bended 
part with a bit of platinum foil, and introduce 
over this small pieces of carbonate of ammo- 
nia till the tube be nearly filled : now seal 
strongly by fusion the open end of the tube ; 
then make the sulphuric acid to run over on 
the carbonate, and leave the tube inclined in 
such a position as that all the acid may drain 
out of the shorter leg. Great care must mean- 
while be taken of the eyes, for the tube is very 
apt to explode. When the clean-drained end 
is afterwards placed in a mixture of ice and 
salt, carbonic acid in the liquid state will 
distil over. 

Liquefied carbonic acid is a limpid colour- 
less body, extremely fluid, which floats upon 
the other contents of the tube, so that the ha- 
zardous process of distillation is hardly neces- 
sary, though this goes on rapidly at the diffe- 
rence of temperature between 32 and 0. 
Its refractive power is much less than that of 
water. Its vapour exerts a pressure of 36 at- 
mospheres at a temperature of 32. As this li- 
quid acid remains in contact with concentrated 
sulphuric acid, it may be inferred to be free 
from water. For this most interesting disco- 
very, and other analogous ones on other gases, 
we are indebted to Mr Faraday. Phil. Tr. 
1823. 



ACID 



27 



CARBONIC. 



The carbonates are characterized by effer- 
vescing with almost all the acids, even the 
acetic, when they evolve their gaseous acid, 
which, passed into lime water by a tube, de- 
prives it of its taste, and converts it into chalk 
and pure water. 

The carbonate of baryta was, by Dr With- 
ering, first found native at Alston Moor in 
Cumberland, in 1783. From this circum- 
stance it has been termed Witherite by Wer- 
ner. See HEAVY SPAR. 

It may be prepared by exposing a solution 
of pure baryta to the atmosphere, when it 
will be covered with a pellicle of this salt by 
absorbing carbonic acid ; or carbonic acid may 
be received into this solution, in which it will 
immediately form a copious precipitate ; or a 
solution of nitrate or muriate of baryta may 
be precipitated by a solution of the carbonate 
of potash, soda or ammonia. The precipitate, 
in either of these cases, being well washed, will 
be found to be very pure carbonate of baryta. 

Carbonate of baryta is soluble only in 
4304 times its weight of cold water, and 2304 
of boiling water, and this requires a long time ; 
but water saturated with carbonic acid dis- 
solves l-830th. It is not altered by exposure 
to the air, but is decomposed by the applica- 
tion of a very violent heat, either in a black- 
lead crucible, or when formed into a paste with 
charcoal powder. Sulphuric acid, in a con- 
centrated state, or diluted with three or four 
parts of water, does not separate the carbonic 
acid with effervescence, unless assisted by heat. 
Muriatic acid does not act upon it likewise, 
unless diluted with water or assisted by heat. 
And nitric acid does not act upon it at all, 
unless diluted. It has no sensible taste, yet 
it is extremely poisonous. 

It is composed of 2.75 parts of acid, and 
9. 75 of baryta. Its prime equivalent is there- 
fore the sum of these numbers = 12.5. 

Carbonate of strontia was first pointed out 
as distinct from the preceding species by Dr 
Crawford, in 1790. See HEAVY SPAR. 

It consists of 6.50 strontia -\- 2.75 carbonic 
acid =9. 25. 

Carbonate of lime exists in great abundance 
in nature. It has scarcely any taste ; is in- 
soluble in pure water, but water saturated 
with carbonic acid takes up l-l500th, though 
as the acid flies off this is precipitated. It 
suffers little or no alteration on exposure to 
the air. When heated it decrepitates, its 
water flies off, and lastly its acid ; but this re- 
quires a pretty strong heat. By this process 
it is burned into lime. 

It is composed of 3.50 lime -f- 2. 75 carbo- 
nic acid = 6.25 ; or in 100 parts, of 56 lime, 
and 44 acid. See CALCAREOUS SPAR, and 
LIMESTONE. 

Carbonate of potash was long known by 
the name of vegetable alkali. 

As water at the usual temperature of the 
air dissolves rather more than its weight of 



this salt, we have thus a ready mode of de- 
tecting its adulterations in general ; and as it 
is often of consequence, in manufactures, to 
know how much alkali a particular specimen 
contains, this may be ascertained by the quan- 
tity of sulphuric acid it will saturate. 

This salt is deliquescent. 

It consists of 6 potash 4- 2.75 carbonic 
acid = 8. 75. 

The bi-carbonate of potash crystallizes, ac- 
cording to Fourcroy, in square prisms, the 
apices of which are quadrangular pyramids. 
According to Pelletier, they are tetraedral 
rhomboidal prisms, with diedral summits. 
The complete crystal has eight faces, two 
hexagons, two rectangles, and four rhombs. 
It has an urinous but not caustic taste, changes 
the syrup of violets green ; boiling water dis- 
solves five-sixths of its weight, and cold water 
one-fourth ; alcohol, even when hot, will not 
dissolve more than 1-1 200th. Its specific 
gravity is 2.012. 

Bi-carbonate of potash melts with a gentle 
heat, loses its water of crystallization, amount- 
ing to T f o> and gives out one-half of its car- 
bonic acid. To obtain the bi-carbonate we 
must saturate the common carbonate with 
carbonic acid, which is best done by passing 
the acid in the state of gas through a solution 
of the salt in twice its weight of water. 

The bi-carbonate is usually called super- 
carbonate by the apothecaries. It consists of 
2 primes of carbonic acid = 5.500, 1 of 
potash = 6, and 1 of water = 1. 125, in all 
12.625. 

Carbonate of soda has likewise been long 
known, and was distinguished from the pre- 
ceding by the name of mineral alkali. In 
commerce it is usually called barilla or soda, 
in which state, however, it always contains a 
mixture of earthy bodies, and usually com- 
mon salt. It may be purified by dissolving it 
in a small portion of water, filtering the solu- 
tion, evaporating at a low heat, and skimming 
off the crystals of muriate of soda as they form, 
on its surface. When these cease to form, 
the solution may be suffered to cool, and the 
carbonate of soda will crystallize. 

One form of it is found in nature. In 
Egypt, where it is collected from the surface 
of the earth, particularly after the desiccation 
of temporary lakes, it has been known from 
time immemorial by the name of nitrum, na- 
tron, or natrum. A carbonate of soda ex- 
ported from Tripoli, which is called Trona 
from the name of the place where it is found, 
and analyzed by Klaproth, contained of soda 
37 parts, carbonic acid 38, water of crystal- 
lization 22.5, sulphate of soda 2. This does 
not effloresce. 

The common carbonate crystallizes in rhom- 
boidal decaedrons, formed by two quadrangu- 
lar pyramids, truncated very near their bases. 
Frequently it exhibits only rhomboidal la- 
mina?. Its specific gravity is 1.3591. Its 



ACID 



28 



CARBONIC. 



taste is urinous, and slightly acrid, without 
being caustic. It changes blue vegetable 
colours to a green. It is soluble in less than 
its weight of boiling water, and twice its 
weight of cold. It is one of the most efflo- 
rescent salts known, falling completely to 
powder in no long time. On the application 
of heat it is soon rendered fluid from the great 
quantity of its water of crystallization ; but is 
dried by a continuance of the heat, and then 
melts. It is somewhat more fusible than the 
carbonate of potash, promotes the fusion of 
earths in greater degree, and forms a glass 
of better quality. Like that, it is very tena- 
cious of a certain portion of its carbonic acid. 
It consists in its dry state of 4 soda -}- 2.75 
acid =6.75. 

But the crystals contain 10 prime propor- 
tions of water. They are composed of 22 
soda -f- 15.3 carbonic acid -f- 62.7 water in 
100 parts, or of 1 prime of soda = 4. 1 of 
carb. acid = 2.75, and 10 of water = 11.25, 
in whole 18. 

Bi-carbonate of soda may be prepared by 
saturating the solution of the preceding salt 
with carbonic acid gas, and then evaporating 
with a very gentle heat to dryness, when a 
white irregular saline mass is obtained. The 
salt is not crystallizable. Its constituents are 
4 soda -j~ 5.50 carb. acid -\- 1. 125 water = 
10.625 ; or in 100 parts, 37.4 soda + 52 acid 
-}- 10. 6 water. The intermediate native com- 
pound, the African trona, consists, according 
to Mr R. Phillips, of 3 primes carbonic acid 
-f- 2 soda -f- 4 water; or in 100 parts, 38 
soda -f 40 acid -f 22 water. See the article 
CARBONATE. 

Carbonate of magnesia, in a state of imper- 
fect saturation with the acid, has been used 
in medicine for some time under the simple 
name of magnesia. It is prepared by pre- 
cipitation from the sulphate of magnesia by 
means of carbonate of potash. Two parts of 
sulphate of magnesia and one of carbonate of 
potash, each dissolved in its own weight of 
boiling water, are filtered and mixed together 
hot: the sulphate of potash is separated by 
copious washing with water ; and the carbon- 
ate of magnesia is then left to drain, and after- 
wards spread thin on paper, and carried to the 
drying stove. When once dried it will be in 
friable white cakes, or a fine powder. 

Another mode of preparing it in the great, 
will be found under the article MAGNESIA. 

The pulverulent carbonate of magnesia of 
the apothecary has a somewhat uncertain com- 
position as to the proportion of acid, earth, 
and water. But there exists in nature a car- 
bonated magnesia in the true equivalent pro- 
portions of 2.75 acid to 2.5 base. See MAG- 
NESITE, and DOLOMITE. 

Carbonate of ammonia, when very pure, is 
in a crystalline form, but seldom very regular. 
Its crystals are so small, that it is difficult to 
determine their figure. The crystals com- 



monly produced by sublimation are little bun- 
dles of needles, or very slender prisms, so 
arranged as to represent herborizations, fern 
leaves, or feathers. The taste and smell of 
this salt are the same with those of pure am- 
monia, but much weaker. It turns the colour 
of violets green, and that of turmeric brown. 
It is soluble in rather more than thrice its 
weight of cold water, and in its own weight 
of hot water ; but a boiling heat volatilizes it. 
When pure, and thoroughly saturated, it is 
not perceptibly alterable in the air ; but when 
it has an excess of ammonia, it softens and 
grows moist. It cannot be doubted, however, 
that it is soluble in air ; for if left in an open 
vessel, it gradually diminishes in weight, and 
its peculiar smell is diffused to a certain dis- 
tance. Heat readily sublimes, but does not 
decompose it 

It has been prepared by the destructive dis- 
tillation of animal substances, and some others, 
in large iron pots, with a fire increased by de- 
grees to a strong red heat ; the aqueous liquor 
that first comes over being removed, that the 
salt might not be dissolved in it. Thus we 
had the salt of hartshorn. Here, however, it 
was much contaminated by a fetid animal oil, 
from which it required to be subsequently 
purified, and is much better fabricated by 
mixing one part of muriate of ammonia and 
two of carbonate of lime, both as dry as pos- 
sible, and subliming in an earthen retort. 

Sir H. Davy has shewn that its component 
parts vary, according to the manner of pre- 
paring it. The lower the temperature at which 
it is formed, the greater the proportion of acid 
and water. Thus, if formed at the tempera- 
ture of 300, it contains more than fifty per 
cent of alkali ; if at 60, not more than twenty 
per cent. 

There are indeed two or three definite com- 
pounds of carbonic acid and ammonia. The 
1st is the solid subcarbonate of the shops. It 
consists of 55 carbonic acid, 30 ammonia, and 
15 water; or probably of 3 primes carbonic 
acid, 2 ammonia, and 2 water; in all 14.75 
for its equivalent. 2d, M. Gay Lussac has 
shewn, that when 100 volumes of ammoniacal 
gas are mixed with 50 of carbonic acid, the 
two gases precipitate in a solid salt, which 
must consist by weight of 56j acid -|~ 43 
alkali, being in the ratio of a prime equivalent 
of each. 3d, When the pungent subcarbo- 
nate is exposed in powder to the air, it be- 
comes scentless by the evaporation of a definite 
portion of its ammonia. It is then a com- 
pound of about 55 or 56 carbonic acid, 21.5 
ammonia, and 22.5 water. It may be repre- 
sented by 2 primes of acid, 1 of ammonia, and 
2 of water, =. 9.875. Another compound, 
it has been supposed, may be prepared by 
passing carbonic acid through a solution of 
the subcarbonate till it be saturated. This, 
however, may be supposed to yield the same 
product as the last salt. M. Gay Lussac in- 



ACID 



29 



CHOLESTER1C. 



fers the neutral carbonate to consist of equal 
volumes of the two gases, though they will not 
directly combine in these proportions. This 
would give 18. 1 to 46.5; the very proportions 
in the scentless salt. For 46.5 : 18. 1 : : 55 : 
21.42. 

The first is well known as a stimulant 
usually put into smelling-bottles, frequently 
with the addition of some odoriferous oil. 

Carbonate ofglucina has been examined by 
Vauquelin, and is, among the salts of that 
earth, that of which he has most accurately 
ascertained the properties. It is in a white, 
dull, clotty powder, never dry, but greasy, 
and soft to the feel. It is not sweet like the 
other salts ofglucina, but insipid. It is very 
light, insoluble in water, perfectly unalterable 
by the air, but very readily decomposed by fire. 

Vauquelin has found, that carbonate of 
zirconia may be formed by evaporating mu- 
riate of zirconia, redissolving it in water, and 
precipitating by the alkaline carbonate. He 
also adds, that it very readily combines so as 
to form a triple salt with either of the three 
alkaline carbonates. See SALT. 

ACID (CASEIC). The name given by 
Proust to an acid found in cheeses, to which 
he ascribes their flavour. 

M. Braconnot shows that the properties 
assigned to caseic acid belong to various sub- 
stances, none of which has any title to be 
considered as a peculiar acid. The substances 
present, according to him, are, free acetic 
acid, aposepedine, animal matter soluble in 
water and insoluble in alcohol ; animal mat- 
ter soluble in both ; a yellow acrid fluid oil, 
* a brown resin,' acetate and muriate of potash, 
and traces of acetate of ammonia. 

ACID (CETIC). The name given by 
M. Chevreul to a supposed peculiar principle 
of spermaceti, which he has lately found to 
be the substance he has called Margarine 
combined with a fatty matter. 

ACID (CEVADIC). By the action of 
potash on the fat matter of the Cevadilla,* there 
is obtained, in the same way as the delphinic, 
the cevadic acid ; only as this is solid, it must 
be separated from the cevadate of baryta, by 
heating this in a retort with phosphoric acid. 
MM. Pelletier and Caventou discovered it. 
It is in the form of needles, or crystalline 
concretions, of a fine white colour. Its odour 
is analogous to that of butyric acid. A heat 
of 20 C. is sufficient to melt it. At a tem- 
perature not much higher, it sublimes in crys- 
talline needles. It is soluble in water, alco- 
hol, ether ; and unites to the bases, forming 
salts of little smell. The cevadate of am- 
monia gives a white precipitate with the salts 
of peroxide of iron. Ann. de Chim. et de 
Phys. xiv. 

* Cevadilla, petite orge, (hordeolum), a plant, ac- 
cording to Haller, belonging to the class of delphinium 
and aconite. It comes from Senegal. There is ano- 
ther called Cevadilla Americana, which is corrosive. 



ACID (CHLORIC). After ACID (MU- 
RIATIC). 

ACID (CHLORIODIC). See ACID 
(HYDRIODIC). 

ACID (CHLOROCARBONIC). See 
CHLORINE, and CHLOROCARBONOUS ACID. 

ACID (CHLOROCYANIC). See in 
the sequel of ACID (HYDROCYANIC). 

ACID (CHOLESTERIC). When we 
treat with nitric acid the fat matter of the 
human biliary calculi, which M. Chevreul 
proposed to call Cholesterine, there is formed, 
according to MM. Pelletier and Caventou, a 
peculiar acid, which they call the Cholesteric. 
To obtain it, they cause the cholesterine to be 
heated with its weight of concentrated nitric 
acid, by which it is speedily attacked and dis- 
solved. There is disengaged at the same time 
much oxide of azote; and the liquor, on cool- 
ing, and especially on the addition of water, 
lets fall a yellow matter, which is the choles- 
teric acid impure, or impregnated with nitric 
acid. It may be purified by repeated wash- 
ings in boiling water. However, after hav- 
ing washed it, it is better to effect its fusion 
in the midst of hot water ; to add to it a small 
quantity of carbonate of lead ; to let the whole 
boil for some hours, decanting and renewing 
the water from time to time; then to put the 
remaining dried mass in contact with alcohol, 
and to evaporate the alcoholic solution. The 
residuum now obtained is the purest possible 
cholesteric acid. 

This acid has an orange-yellow colour when 
it is in mass ; but it appears in white needles 
(whose form it is difficult to determine) when 
we dissolve it in alcohol, and leave it to 
spontaneous evaporation. Its taste is very 
feeble, slightly styptic, and resembles that of 
butter. Its specific gravity is intermediate 
between that of alcohol and water. It fuses 
at 58 C., and is not decomposed till the 
temperature be raised much above that of 
boiling water. It then affords oil, water, car- 
bonic acid, and carburetted hydrogen, but no 
trace of ammonia. It is very soluble in alco- 
hol, sulphuric and acetic ether, in the volatile 
oils of lavender, rosemary, turpentine, berga- 
mot, &c. It is, on the other hand, insoluble 
in the fixed oils of olives, sweet almonds, and 
castor oil. It is equally so in the vegetable 
acids, and almost entirely insoluble in water, 
which takes up merely enough to make it 
redden litmus. Both in the cold and with 
heat, nitric acid dissolves without altering it. 
Concentrated sulphuric acid acting on it for 
a considerable time, only carbonizes it. 

It appears that the cholesteric acid is capa- 
ble of uniting with the greater part of the 
salifiable bases. All the resulting salts are 
coloured, some yellow, others orange, and 
others red. The cholesterates of potash, soda, 
ammonia, and probably of morphia, are very 
soluble and deliquescent; almost all the others 
are insoluble, or nearly so. There is none of 



ACID 30 

them which cannot be decomposed by all the 
mineral acids, except the carbonic, and by the 
greater part of the vegetable acids ; so that on 
pouring one of these acids into a solution of 
the cholesterate, the cholesteric acid is in- 
stantly separated in flocks. The soluble cho- 
lesterates form precipitates in all the metallic 
solutions, whose base has the property of 
forming an insoluble or slightly soluble salt 
with cholesteric acid. 

MM. Pelletier and Caventou found the cho- 
lesterate of baryta to consist of 100 of acid, 
and 56.259 base; whence the prime equiva- 
lent of the former appears to be about 17.35. 
Yet they observed, on the other hand, that on 
treating the cholesterate of lead with sulphuric 
acid, they obtained as much sulphate of lead 
as of cholesterate. From this experiment, the 
equivalent of the dry acid would seem to be 
5 : hence we may imagine, that when the 
cholesteric acid unites to the oxide of lead, 
and in general to all the oxides which have a 
slight affinity for oxygen, there takes place 
something similar to what happens in the 
reaction of oxide of lead and oxalic acid 
Journ. de Pharm. iii. 292. 

ACID (CHROMIC). This acid was at 
first extracted from the red lead ore of Siberia, 
by treating this ore with carbonate of potash, 
and separating the alkali by means of a more 
powerful acid. In this state it is impure, 
forming a red or orange-coloured powder, of a 
peculiar rough metallic taste. If this powder 
be exposed to the action of light and heat, it 
loses its acidity, and is converted into green 
oxide of chrome, giving out pure oxygen gas. 

To obtain pure chromic acid, we must dis- 
til fluor-spar, chromate of lead (the yellow 
pigment), and sulphuric acid (anhydrous?) in 
a leaden retort, when a gaseous mixture of 
chromic and fluoric acids is evolved, that is 
readily absorbable by water. This mixed gas 
affords a thick orange smoke, and on coming 
in contact with air, deposits small red crystals 
of chromic acid. Ammoniacal gas introduced 
into this gas, contained in glass jars lined with 
resin, burns with explosion. Crystals of chro- 
mic acid are also decomposed in ammoniacal 
gas with a flash of light, and become protoxide 
of chromium. Water, by absorbing this 
mixed gas, acquires an orange tint; from 
which, by evaporation, pure chromic acid is 
obtained, the fluoric being volatilized. If the 
gas be received in a deep and moistened pla- 
tinum vessel, it descends, saturates the water, 
and is then entirely absorbed by the fluoric 
acid, which is at length dissipated, the vessel 
becoming filled with a red snow, consisting of 
chromic acid. This crystalline matter, when 
heated to redness in a platinum dish, fuses, 
explodes with a flash, and resolves itself into 
protoxide and oxygen. The crystals obtained 
from the water do not present this pheno- 
menon. 

M. Maus prepares chromic acid as follows : 



CHROMIC. 

A hot and concentrated solution of the bi- 
chromate of potash is to be decomposed by 
fluosilicic acid ; the liquid is to be filtered 
and evaporated to dryness; the acid thus 
dried is to be dissolved in as small a quantity 
of water as possible, and the clear fluid de- 
canted from the deposit of fluosilicate of pot- 
ash which has passed the filter. The separa- 
tion of this portion must not be made by a 
filter, for in this state the chromic acid attacks 
the paper, and is itself converted into oxide 
of chrome. 

To prepare the fluosilicic acid in sufficient 
quantity, M. Maus uses a very large retort 
with a long neck. He puts into it the mix- 
ture of fluor-spar and glass, and adds sulphu- 
ric acid to about three times the amount of 
the fluor-spar in weight, and mixes the whole 
well. A large globe with a long neck is then 
provided, and a sufficient quantity of water 
put into it ; the neck of the retort is intro- 
duced, the globe shaken to moisten the inte- 
rior with water, and the fluosilicic gas evolv- 
ed by the application of heat. When it ar- 
rives in the globe it condenses in the water, 
and as soon as the quantity of silica produced 
retards the contact of the gas and water, the 
globe is again shaken and the operation con- 
tinued. In this way no gas escapes, and the 
water soon becomes saturated with the acid ; 
the silica is easily separable. 

Chromic acid is soluble in water, and crys- 
tallizes, by cooling and evaporation, in long- 
ish prisms of a ruby red. Its taste is acrid 
and styptic. Its specific gravity is not ex- 
actly known ; but it always exceeds that of 
water. It powerfully reddens the tincture of 
turnsole. 

Its action on combustible substances is 
little known. If it be strongly heated with 
charcoal, it grows black, and passes to the 
metallic state without melting. 

Of the acids, the action of the muriatic on 
it is the most remarkable. If this be distilled 
with the chromic acid, by a gentle heat, it is 
readily converted into chlorine. It likewise 
imparts to it by mixture the property of dis- 
solving gold ; in which the chromic resembles 
the nitric acid. This is owing to the weak 
adhesion of its oxygen, and it is the only one 
of the metallic acids that possesses this pro- 
perty. 

The extraction of chromic acid from chrome 
ore is also performed by igniting it with its own 
weight of nitre in a crucible. The residue is 
lixiviated with water, which being then filtered 
contains the chromate of potash. On pouring 
into this a little nitric acid and muriate of 
baryta, an instantaneous precipitate of the 
chromate of baryta takes place. A fter having 
procured a certain quantity of this salt, it 
must be put in its moist state into a capsule, 
and dissolved in the smallest possible quan- 
tity of weak nitric acid. The baryta is to be 
then precipitated by very dilute sulphuric 



ACID 



CITRIC. 



acid, taking care not to add an excess of it. 
When the liquid is found by trial to contain 
neither sulphuric acid nor baryta, it must be 
filtered. It now consists of water, with nitric 
and chromic acids. The whole is to be eva- 
porated to dryness, conducting the heat at the 
end so as not to endanger the decomposition 
of the chromic acid, which will remain in the 
capsule under the form of a reddish matter. 
It must be kept in a glass phial well corked. 

Chromic acid, heated with a powerful acid, 
becomes chromic oxide; while the latter, 
heated with the hydrate of an alkali, becomes 
chromic acid. As the solution of the oxide 
is green, and that of the acid yellow, these 
transmutations become very remarkable to the 
eye. From Berzelius's experiments on the 
combinations of the chromic acid with baryta 
and oxide of lead, its prime equivalent seems 
to be 6.5; consisting of 3.5 chromium, and 
3.0 oxygen. See CHROMIUM. 

It readily unites with alkalis, and is the 
only acid that has the property of colouring 
its salts, whence the name chromic has been 
given it. 

Chromate of potash is obtained from the 
ferriferous chrome ore, by igniting it with 
nitre, as described above. By careful eva- 
poration it may be obtained in crystals, the 
usual form of which is four-sided prisms ter- 
minated by dihedral summits, or oblique four- 
sided prisms terminated by four-sided pyra- 
mids. Their colour is bright yellow. Their 
taste is cooling and disagreeable. Water at 
60 dissolves about half its weight of this salt, 
and boiling water much more. It is insoluble 
in alcohol. Its specific gravity is 2.6. Heat 
causes the salt to assume a transient red tint, 
which passes into yellow on cooling. It con- 
tains no water of crystallization. Its constitu- 
ents are chromic acid 6.5, potash 6,= 12.5. 

To test chromate of potash, add a large ex- 
cess of tartaric acid, which decomposes the 
chromic acid, and gives the whole the ame- 
thystine hue of tartrate of chromium. If 
the chromate has been pure, this liquid will 
afford no precipitate with the nitrates of ba- 
ryta or silver ; whence the absence of muri- 
ate or sulphate of potash may be readily as- 
certained. Nitre may be detected by the 
fumes of nitric acid disengaged by pouring a 
little sulphuric acid on the salt. 

Bi-chromate of potash is easily formed, by 
adding to a saturated solution of the yellow 
chromate some dilute nitric acid. On heat- 
ing the mixture, the orange precipitate, which 
ensues on the addition of the nitric acid, is 
dissolved, and, by slow cooling, fine crystals 
of bi-chromate may be obtained. Their form 
is that of square tables with bevelled edges, or 
flat four-sided prisms. They are permanent 
in the air. Their taste is metallic and bitter. 
Water at 60 dissolves about one-tenth of 
this salt ; but boiling water dissolves nearly 
half its weight. It is not soluble in alcohol. 



Its sp. gr. is 1.98. It is anhydrous. It 
consists of chromic acid 13, potash 6, = 19. 

Chromate of baryta is very little soluble. 

Mr Henry Stokes has described three new 
double chromates, obtained by adding chro- 
mate of potash to sulphate of zinc, and also to 
sulphate of nickel, and to sulphate of copper. 
They all contain very little chromic acid, are 
pretty soluble in water, crystallize in tables, 
and undergo no change in the atmosphere. 
In 100 parts of the zinc salt, there are only 
one-third of a part of chromic acid, and not 
two parts in 100 of the nickel salt. 

When chromic acid is melted with borax, or 
its glass, or acid of phosphorus, it communi- 
cates to it a beautiful emerald-green colour. 

If paper be impregnated with it, and ex- 
posed to the sun a few days, it acquires a 
green colour, which remains permanent in 
the dark. 

ACID (CHROMO-SULPHURIC). 
When chromate of baryta is treated with di- 
lute sulphuric acid in excess, the liquid, on 
being filtered and evaporated, lets fall little 
quadrangular prisms of a deep red colour. 
These crystals, which may also be obtained 
by mingling chromic and sulphuric acids in 
a proper state of concentration, are obvious- 
ly a compound of the two acids in atomic 
proportions, stated by M. Gay Lussac at 
1303.64. chromic acid, and 50) . 16 sulphuric. 
By our numbers, there are thus two atoms 
of the chromic to one of the sulphuric acid. 
This compound acid is deliquescent. When 
the alcoholic solution is highly concentrated 
it explodes, while the chromic acid is con- 
verted into the green oxide of chrome, with 
the simultaneous production of a little sul- 
phuric ether and sweet oil of wine. 

ACID (CHYAZIC). See ACIDS (HY- 
DROCYANIC and FERROCYANIC). 

ACID (CITRIC). To procure this acid, 
boiling lemon-juice is to be saturated with 
powdered chalk, the weight of which is to be 
noted; and the powder must be stirred up 
from the bottom, or the vessel shaken from 
time to time. The neutral saline compound 
falls to the bottom, while the mucilage re- 
mains suspended in the watery fluid, which 
must be decanted off; the remaining precipi- 
tate must then be washed with warm water 
until it comes off clear. To the powder thus 
edulcorated, a quantity of sulphuric acid, 
equal the chalk in weight, and diluted with 
ten parts of water, must be added, and the 
mixture boiled a few minutes. The sulphu- 
ric acid combines with the earth, and forms 
sulphate of lime, which is left when the 
cold liquor is filtered, while the disengaged 
acid of lemons remains dissolved in the fluid. 
This last must be evaporated to the consist- 
ence of a thin syrup, which yields the pure 
citric acid in little needle-like crystals. It is 
necessary that the sulphuric acid should be 
rather in excess, because the presence of a 



ACID 



32 



CROCONIC. 



small quantity of lime will prevent the crys- 
tallization. 

To have it perfectly pure, it must be re- 
peatedly crystallized ; and thus it forms very 
large and accurately defined crystals in rhom- 
boidal prisms, the sides of which are inclined 
in angles of 60 and 120, terminated at each 
end by tetraedrai summits, which intercept 
the solid angles. 

Its taste is extremely sharp, so as to appear 
caustic. It is among the vegetable acids the 
one which most powerfully resists decompo- 
sition by fire. 

In a dry and warm air it seems to efflo- 
resce ; but it absorbs moisture when the air 
is damp, and at length loses its crystalline 
form. A hundred parts of this acid are so- 
luble in seventy-five of water at 60, accord- 
ing to Vauquelin. Though it is less alter- 
able than most other solutions of vegetable 
acids, it will undergo decomposition when 
long kept. 

The crystals of citric acid, according to 
Berzelius, contain 79 per cent of real acid. 
The rest is water. The same chemist found 
from citrate of lead that the prime equivalent 
of the crystals was 9.5, while that of the real 
acid was 7.368; and its constituents were 
oxygen 54.831, carbon 41.369, hydrogen 
3.800. My own experiments on citric acid 
led me to conclude that its prime equivalent 
in the crystalline state was 8.375 ; and that it 
consisted of oxygen 59.7, carbon 35.8, and 
hydrogen 4.5. Two atoms of oxygen and 
two of hydrogen separate when citric acid is 
combined with oxide of lead in what is called 
the dry citrate of this metal. The prime 
equivalent of the acid in this state becomes 
6. 125. Dr Prout finds the crystals of citric 
acid to consist of carbon 34.28, water 42.85. 
and oxygen 22.87. Vauquelin found that 
36 parts of crystallized citric acid took for sa- 
turation 6 1 of bi-carbonate of potash. Hence 
the prime equivalent of such acid is 7.45; 
between which, and the number given by Ber- 
zelius, mine is nearly the mean. Dr Prout's 
analysis accords closely with mine; his total 
oxygen being 60.95, and his hydrogen 4.77. 

If a solution of baryta be added gradually 
to a solution of citric acid, a flocculent preci- 
pitate is formed, soluble by agitation, till the 
whole of the acid is saturated. This salt at 
first falls down in powder, and then collects 
in silky tufts, and a kind of very beautiful 
and shining silvery bushes. It requires a 
large quantity of water to dissolve it. 

The citrate of lime has been mentioned 
already, in treating of the mode of purifying 
the acid. 

The citrate of potash is very soluble and 
deliquescent. 

The citrate of soda has a dull saline taste ; 
dissolves in less than twice its weight of 
water; crystallizes in six-sided prisms with 
flat summits; effloresces slightly, but does 



not fall to powder ; boils up, swells, and is 
reduced to a coal on the fire.- 

Citrate of ammonia is very soluble ; does 
not crystallize unless its solution be greatly 
concentrated ; and forms elongated prisms. 

Citrate of magnesia does not crystallize. 

The citric acid is found in many fruits 
united with the malic acid ; which see, for 
the process of separating them in this case. 

Citric acid being more costly than tartaric, 
may be occasionally adulterated with it. This 
fraud is discovered, by adding slowly to the 
acid dissolved in water a solution of carbonate 
of potash, which will give a white pulverulent 
precipitate of tartar, if the citric be contami- 
nated with the tartaric acid. When one part 
of citric acid is dissolved in 19 of water, the 
solution may be used as a substitute for lemon 
juice. If before solution the crystals be tri- 
turated with a little sugar and a few drops of 
the oil of lemons, the resemblance to the na- 
tive juice will be complete. It is an antidote 
against sea scurvy; but the admixture of 
mucilage and other vegetable matter in the 
recent fruit of the lemon, has been supposed 
to render it preferable to the pure acid of the 
chemist. See SALT. 

ACID(COLUMBIC). The experiments 
of Mr Hatchett have proved, that a peculiar 
mineral from Massachusetts, deposited in the 
British Museum, consisted of one part of 
oxide of iron, and somewhat more than three 
parts of a white-coloured substance, possessing 
the properties of an acid. Its basis was me- 
tallic. Hence he named this Columbium, 
and the acid the Columbic. Dr Wollaston, 
by very exact analytical comparisons, proved, 
that the acid of Mr Hatchett was the oxide 
of the metal lately discovered in Sweden, by 
Mr Ekeberg, in the mineral yttrotantalite, 
and thence called tantalum. Dr Wollaston's 
method of separating the acid from the mi- 
neral is peculiarly elegant. One part of tan- 
talite, five parts of carbonate of potash, and 
two parts of borax, are fused together in a 
platina crucible. The mass, after being sof- 
tened in water, is acted on by muriatic acid. 
The iron and manganese dissolve, while the 
columbic acid remains at the bottom. It is 
in the form of a white powder, which is in- 
soluble in nitric and sulphuric acids, but par- 
tially in muriatic. It forms with baryta an 
insoluble salt, of which the proportions, ac- 
cording to Berzelius, are 24.4 acid, and 9.75 
baryta. By oxidizing a portion of the re- 
vived tantalum or columbium, Berzelius con- 
cludes the composition of the acid to be 100 
metal and 5.485 oxygen. 

ACID (CROCONIC). When potassium 
is prepared from calcined tartar by Brunner's 
method, a gas is evolved which deposits a 
greyish-brown substance on cold bodies. This 
substance, with a little water, is separated 
into two parts; one very soluble, yielding a 
brownish-yellow liquid, which, spontaneously 



ACID 



33 



FLUORIC. 



concentrated, furnishes an acicular orange- 
coloured salt. This salt, purified by repeated 
crystallization, has been called by M. Ginelin 
croconate of potash, because it contains a yel- 
low acid which yields many combinations of 
the same colour. 

Croconate of potash is neutral, inodorous, 
having a weak taste like that of nitre. Its 
primitive form is a rhomboid of 106 and 
74. Croconic acid is obtained by treating 
this salt with absolute alcohol, to which a 
little sulphuric acid has been added ; sulphate 
of potash is formed, and the CROCONIC ACID 
is dissolved. It crystallizes in grains or nee- 
dles ; is transparent, of a fine yellow colour, 
inodorous, of a rough acid taste, and reddens 
litmus. M. Gmelin thinks that this acid is 
a hydracid like the prussic. Hydrocroconic 
acid consists of carbon 23.23, hydrogen 0.77, 
oxygen 24.81, water 13.98, which in the salt 
of potash are united with 37.21 of that al- 
kali. 

ACID (CYANIC). See in the sequel of 
ACID (HYDROCYANIC). 

ACID (DELPHINIC). The name 
given by M. Chevreul to a substance which 
he has extracted from the oil of the dolphin. 
It resembles a volatile oil ; has a light lemon 
colour, and a strong aromatic odour, analo- 
gous to that of rancid butter. Its taste is 
pungent, and its vapour has a sweetened taste 
of ether. Its density at 14 C. is 0.941. It 
is slightly soluble in water, and very soluble 
in alcohol. The latter solution strongly red- 
dens litmus. 100 parts of delphinic acid 
neutralize a quantity of base which contains 
9 of oxygen, whence its prime equivalent 
appears to be 11. 1 1. Ann. de Chim. et de 
Phys. vii. 

ACID (ELLAGIC). The deposit which 
forms in infusion of nut-galls left to itself, is 
not composed solely of gallic acid and a mat- 
ter which colours it; it contains, besides, a 
little gallate and sulphate of lime, and a new 
acid, which was pointed out for the first time 
by M. Chevreul in 1815 an acid on which 
M. Braconnot made observations in 1818, 
and which he proposed to call acid ellayic, 
from the word galle reversed. Probably this 
acid does not exist ready formed in nut-galls. 
It is insoluble ; and, carrying down with it 
the greater part of the gallic acid, forms the 
yellowish crystalline deposit. But boiling 
water removes the gallic acid from the ella- 
gic ; whence the means of separating them 
from one another. Ann. de Chim. et de 
Phys. ix. 181. 

ACIDS (FERROCYANIC and FER- 
RURETTED CHYAZIC). See in the 
sequel of ACID (HYDROCYANIC). 

ACID (FLUORIC). The powder of 
crystallized fluor-spar is to be put into a silver 
or leaden alembic, and its own weight of sul- 
phuric acid poured over it. Adapt to the 
alembic a silver or leaden tube terminating in 



a receiver of the same metal, surrounded by 
ice. On applying a moderate heat to the 
alembic, the fluoric acid will rise in vapours, 
which will condense in the receiver into an 
intensely active liquid, first procured by M. 
Gay Lussac, and since examined by Sir H. 
Davy. 

It has the appearance of sulphuric acid, 
but is much more volatile, and sends oft' 
white fumes when exposed to air. Its spe- 
cific gravity is only 1.0609. It must be ex- 
amined with great caution, for when applied 
to the skin it instantly disorganizes it, and 
produces very painful wounds. When pot- 
assium is introduced into it, it acts with in- 
tense energy, and produces hydrogen gas and 
a neutral salt: when lime is made to act 
upon it, there is a violent heat excited, water 
is formed, and the same substance as fluor- 
spar is produced. With water, in a certain 
proportion, its density increases to 1.25. 
When it is dropped into water, a hissing 
noise is produced with much heat, and an 
acid fluid, not disagreeable to the taste, is 
formed, if the water be in sufficient quantity. 
It instantly corrodes and dissolves glass. 

In order to insure the absolute purity of 
the acid, the first portions that come over 
may be set apart, as possibly containing some 
silicated fluoric acid, if any silica was present 
in the spar. 

Considerable difference of opinion prevails 
concerning the prime equivalent of this acid, 
as it exists in its dry combinations. Sir H. 
Davy states, that 100 fluor-spar yield 175.2 
sulphate of lime ; whence we deduce the 
prime equivalent of fluoric acid to be 1 .35, to 
lime 3.5, and oxygen 1.00. Berzelius, in 
his last series of experiments, gives from 
fluate of lime 1.357, for the equivalent of 
fluoric acid. 

Of all the fluates which he analyzed, that 
of lime was the only one which he succeeded 
in freeing perfectly from the last portions of 
silica; and hence he regards the above re- 
sult as quite satisfactory. In three experi- 
ments, in which he saturated carbonate of 
lime with pure fluoric acid, evaporated to 
dryness and ignited, he obtained from 100 
parts of such fluate, on decomposing it by 
sulphuric acid, 174.9, 175, and 175.12, of 
ignited sulphate of lime. Annales de Chim. 
etde Phys. 1824. This accordance between 
Sir H. Davy's result with the native fluate, 
and that of Berzelius with the artificial, 
seems decisive. 

Berzelius observes, that fluate of lime can 
be prepared only by saturating the recently 
precipitated moist carbonate with pure fluoric 
acid. The fluate is thus obtained as granu- 
lar as the carbonate, and may be washed; 
whereas, if prepared by double decomposi- 
tion, we obtain a jelly which does not change 
even by evaporation, and which cannot be 
washed. 

C 



ACID 



34 



FLUORIC. 



Dr Thomson, in his elaborate work on 
the first principles of Chemistry, assigns 1.25 
as the prime equivalent of fluoric acid. He 
deduced this number from the quantity of 
chloride of calcium, and of chloride of ba- 
rium, to which a certain weight of fluate of 
soda was found to be equivalent in the way 
of double decomposition. But his fluate of 
soda was prepared in a very questionable 
manner; by adding carbonate of soda in 
small quantities to a solution of carbonate of 
ammonia, previously saturated with silicated 
fluoric gas; evaporating the whole to dry- 
ness ; redissolving and evaporating till the 
fluate of soda crystallized in transparent 
crusts. As a fluosilicate of ammonia exists, 
possibly some of this may have been formed, 
of which some silica might remain associated 
with his soda. Nor does his fluate of soda 
correspond in character to the description of 
this salt directly formed by Berzelius, by sa- 
turating carbonate of soda with pure fluoric 
acid. By spontaneous evaporation, fluate of 
soda is obtained in transparent cubes, or re- 
gular octahedrons ; by heat, in groups of 
small cubical grains. It contains no water 
of crystallization, and is more difficult of 
fusion by heat than glass. At the tempera- 
ture of 60 F. 100 parts of water dissolve 
only 4.8 parts of it ; and at the boiling point 
only 4.3. Dr Thomson says, that he dis- 
solved 5.25 grains of his salt (white crusts, 
freed by ignition from their water of crystal- 
lization) in a little water. From the mode of 
preparing his primary salt, from its appear- 
ance, and from the defect in the process of 
double decomposition for forming pure fluate 
of lime, Dr Thomson's atomic number seems 
entitled to little confidence. 

Fluoric acid may either be regarded as a 
compound of oxygen with an unknown base 
to be called fluor ; or of hydrogen with an 
electro-negative element to be called fluorine. 
If fluor-spar consist of lime associated with 
an oxygen acid, then this will contain one 
prime proportion of oxygen = 1, combined 
with one prime of fluor = 0.357. Were 
this latter number 0.375, to which it ap- 
proaches, it would equal the weight of three 
atoms of hydrogen. But if fluor-spar be 
truly a fluoride of calcium, then, from its 
prime equivalent 4.857, we deduct the prime 
equivalent of calcium 2.5, and the remainder 
2.357 will be the prime of fluorine, a number 
nearly 19 times that of hydrogen. 

From the remarkable property possessed by 
fluoric acid of dissolving silica, it has been 
employed for etching on glass, both in the 
gaseous state and combined with water. The 
glass is previously coated with white bees' 
wax ; on which the figures are traced with a 
sharp point. 

With the view of separating its hydrogen, 
Sir H. Davy applied the power of the great 
voltaic batteries of the Royal Institution to 



the liquid fluoric acid. " In this case, gas 
appeared to be produced from both the ne- 
gative and positive surfaces ; but it was pro- 
bably only the undecompounded acid, ren- 
dered gaseous, which was evolved at the posi- 
tive surface; for during the operation the 
fluid became very hot, and speedily diminish- 
ed." " In the course of these investigations 
I made several attempts to detach hydrogen 
from the liquid fluoric acid, by the agency of 
oxygen and chlorine. It was not decomposed 
when passed through a platina tube heated 
red-hot with chlorine, nor by being distilled 
from salts containing abundance of oxygen, 
or those containing abundance of chlorine." 
The marvellous activity of fluoric acid may 
be inferred from the following remarks of 
Sir H. Davy ; from which also may be esti- 
mated in some measure, the prodigious diffi- 
culty attending refined investigations on this 
extraordinary substance. 

" I undertook the experiment of electriz- 
ing pure liquid fluoric acid with considerable 
interest, as it seemed to offer the most proba- 
ble method of ascertaining its real nature; 
but considerable difficulties occurred in exe- 
cuting the process. The liquid fluoric acid 
immediately destroys glass, and all animal 
and vegetable substances ; it acts on all 
bodies containing metallic oxides; and I 
know of no substances which are not rapidly 
dissolved or decomposed by it, except metals, 
charcoal, phosphorus, sulphur, and certain 
combinations of chlorine. I attempted to 
make tubes of sulphur, of muriates of lead, 
and of copper containing metallic wires, by 
which it might be electrized, but without suc- 
cess. I succeeded, however, in boring a piece 
of horn silver, in such a manner that I was 
able to cement a platina wire into it by means 
of a spirit lamp ; and by inverting this in a 
tray of platina, filled with liquid fluoric acid, 
I contrived to submit the fluid to the agency 
of electricity in such a manner, that, in suc- 
cessive experiments, it was possible to collect 
any elastic fluid that might be produced. 
Operating in this way with a very weak vol- 
taic power, and keeping the apparatus cool 
by a freezing mixture, I ascertained that the 
platina wire at the positive pole rapidly cor- 
roded, and became covered with a chocolate 
powder ; gaseous matter separated at the ne- 
gative pole, which I could never obtain in 
sufficient quantities to analyze with accuracy, 
but it inflamed like hydrogen. No other in- 
flammable matter was produced when the 
acid was pure." M. Knhlmann transmitted 
anhydrous sulphuric acid in vapour, over 
ignited fluor-spar contained in a platinum 
tube, but no change ensued. The acid was 
recondensed in part in the farthest tube, and 
no trace of fluoric acid was perceptible. 
But when a little water was added to the 
sulphuric acid, the fluoric was instantly dis- 
engaged from the spar. 



ACID 



35 



FLUOSILICIC. 



The same chemist decomposed fluor-spar 
by transmitting dry muriatic acid gas over it 
ignited in a tube. Chloride of lime remain- 
ed in the tube, and pure hydrofluoric gas 
came over. 100 parts of the fluoride of 
calcium (fluor-spar), thus treated, became 
143.417 parts of chloride of calcium, con- 
sisting of 52.819 parts of calcium, (present 
in 100 of fluor-spar), united to 90.598 of 
chlorine). But this latter quantity must 
have liberated 2.511 parts of hydrogen, says 
M. Kuhlmann, which must therefore have 
combined with the 47.181 parts of fluorine 
in the spar, to form 49.692 parts of hydro- 
fluoric acid. This must consist then of 
94.941 parts of fluorine, and 5.059 hydro- 
gen, in 100. 

The salts formed by fluoric acid and seve- 
ral bases, have been lately examined by M. 
Berzelius with his accustomed precision. 

Superfluate of potash. This acid fluate is 
obtained by mixing with the acid a quantity 
of potash, insufficient to saturate it. On 
concentrating the solution, a little of the re- 
dundant acid flies off, but the greater part 
remains and crystallizes with the alkali. This 
Salt, when heated, fuses, and leaves 74.9 per 
cent of neutral fluate, while fumes of fluoric 
acid are volatilized. Berzelius regards the 
above acid salt as composed of an atom of 
fluate of potash, and an atom of hydrated 
fluoric acid. 

Fluate of potash is prepared by saturating, 
imperfectly, fluoric acid with carbonate of 
potash, evaporating and heating so as to expel 
the excess of acid. It has a sharp saline 
taste, is very alkaline, and deliquesces in the 
air. It crystallizes very difficultly in water, 
and then forms cubes or rectangular prisms, 
with stair-like scales, similar to common salt. 
Acid fluate of soda. This salt is little so- 
luble in cold water. By a slow spontaneous 
evaporation it affords rhomboidal crystals, 
having a sharp taste, and distinctly acid. 
Heat separates the fluoric acid in a concen- 
trated state, without changing the form of 
the crystals, and 68. 1 per cent of neutral 
fluate remain. Berzelius considers this salt 
to be a compound of an atom of fluate of 
soda, and an atom of hydrated fluoric acid. 

Neutral fluate of soda. This salt may be 
obtained directly from fluoric acid and car- 
bonate of soda, or by decomposing 100 parts 
of the double fluate of soda and silica, by 1 12 
parts of dried carbonate of soda. When the 
salt is pure, and left to spontaneous evapora- 
tion, it affords transparent cubes of regular 
octahedrons, which often present a pearly 
lustre. Octahedrons are always obtained 
when the solution contains some carbonate 
of soda, but on the contrary, groups of small 
cubic grains when the evaporation is pro- 
duced by elevation of temperature. The 
fluates of potash and soda are isomorphous 
with the muriates of the same bases. Fluate 



of soda melts with more difficulty than glass. 
100 parts of water at 60 F. dissolve 4.8 of 
it; and at the boiling point only 4.3. 

Add fluate of ammonia forms small gra- 
nular crystals, which deliquesce. 

Neutral fluate of ammonia is more volatile 
than sal ammoniac. It is easily obtained by 
heating one part of dry sal ammoniac with a 
little more than two parts of fluate of soda, 
in a crucible of platinum with its lid turned 
upwards. Into this lid a little cold water is 
put, while the bottom of the crucible is heat- 
ed with a spirit of wine lamp. The fluate of 
ammonia thus sublimes perfectly pure in a 
mass of small prismatic crystals. It fuses 
before subliming, and acts on glass even in 
its dry state, and at ordinary temperatures. 

The earthy fluates are best prepared by 
digesting their recently precipitated moist 
carbonates in an excess of fluoric acid. That 
of baryta is slightly soluble in water, and 
readily in muriatic acid. 

ACID (FLUOSILICIC). If instead of 
being distilled in metallic vessels, the mixture 
of fluor-spar and oil of vitriol be distilled in 
glass vessels, little of the corrosive liquid will 
be obtained ; but the glass will be acted upon, 
and a peculiar gaseous substance will be pro- 
duced, which must be collected over mercury. 
The best mode of procuring this gaseous body 
is to mix the fluor-spar with pounded glass or 
quartz ; and in this case, the glass retort may 
be preserved from corrosion, and the gas ob- 
tained in greater quantities. This gas, which 
is called silicated fluoric gas, is possessed of 
very extraordinary properties. 

It is very heavy; 100 cubic inches of it 
weigh 1 10.77 gr. ; and hence its sp. gr. is to 
that of air as 3.632 is to 1.000. It is about 
48 times denser than hydrogen. When 
brought into contact with water, it instantly 
deposits a white gelatinous substance, which 
is hydrate of silica ; it produces white fumes 
when suffered to pass into the atmosphere. 
It is not affected by any of the common 
combustible bodies; but when potassium is 
strongly heated in it, it takes fire, and burns 
with a deep red light ; the gas is absorbed, and 
a fawn-coloured substance is formed, which 
yields alkali to water with slight effervescence, 
and contains a combustible body. The wash- 
ings afford potash, and a salt, from which the 
strong acid fluid previously described may 
be separated by sulphuric acid. 

The gas formed by the action of liquid 
sulphuric acid on a mixture containing silica 
and fluor-spar, the silicated fluoric gas or fluo- 
silicic acid, may be regarded as a compound 
of fluoric acid and silica. It affords, when 
decomposed by solution of ammonia, 61.4 
per cent of silica ; and hence was at first sup- 
posed by Sir H. Davy to consist of two prime 
proportions of acid = 2.652, and one of silica 
= 4.066, the sum of which numbers might 
represent its equivalent = 6.718. One 



ACID 



36 



FLUOBORIC. 



volume of it condenses two volumes of am- 
monia; and they form together a peculiar 
saline substance, which is decomposed by 
water. The composition of this salt is easily 
reconciled to the numbers given as represent- 
ing silica and fluoric acid, on the supposition 
that it contains one prime of ammonia to one 
of the fluosilicic gas ; for 200 cubic inches of 
ammonia weigh 36.2 gr. and 100 of the acid 
gas 1 10.77. Now 36.2 : 2. 125 :: 1 10.77 : 
6.5024, 

Dr John Davy obtained, by exposing that 
gas to the action of water, ^Vo f i ts weight 
of silica ; and from the action of water of 
ammonia he separated T Vo 4 o f ^ ts weight. 
Hence 100 cubic inches consist by weight of 
68 silica and 42 of unknown fluoric matter, 
the gas which holds the silica in solution. Sir 
H. Davy, however, latterly, conceives that 
this gas is a compound of the bases of silica, 
or silicon, with fluorine, the supposed basis 
of fluoric acid. 

Berzelius, in his late elaborate researches on 
the fluoric combinations, (Annales de Chim. 
et de Phys. xxvii. 289.), says that the silicated 
fluoric acid should be regarded as nothing else 
than fluate of silica, for it is only with the 
neutral fluates that it can unite without suf- 
fering decomposition ; and that when a por- 
tion of silica has been separated from it, it 
can be replaced only by an alkali, an oxide, 
or water. When he put silicated fluoric gas 
in contact with carbonate of potash or soda, 
reduced to a very fine powder, there was no 
more of it absorbed than what might be as- 
cribed to moisture contained in the carbonate; 
and the salt, after exposure to the gas for se- 
veral days, had absorbed but an extremely 
small portion of it. The same result is ob- 
served with pure lime and the bicarbonate of 
potash. But the gas is very easily absorbed 
when exposed, even without moisture, to a 
finely pulverized fluate, either with an alka- 
line, earthy, or metallic base. At the end of 
a few hours the fluate is completely saturated 
with the gas; showing that the portion of 
fluoric acid and silica absorbed, has no need 
of any new base for its saturation. This sim- 
ple fact shows that the pretended fluosilicates, 
instead of being combinations of a fluate with 
a silicate, are rather combinations of fluate of 
silica with fluates of the other bases. M. 
Berzelius infers from his experiments, that 
fluate of silica is formed of 100 parts fluoric 
acid, and 144.5 silica. Water separates one- 
third of this silica. 

ACID (FLUOBORIC). If, instead of 
glass or silica, the fluor-spar be mixed with dry 
vitreous boracic acid, and distilled in a glass 
vessel with sulphuric acid, the proportions be- 
ing one part boracic acid, two fluor-spar, and 
twelve oil of vitriol, the gaseous substance 
formed is of a different kind, and is called the 
fluoboric gas. 100 cubic inches of it weigh 
73.5 gr. according to Sir H. Davy, which 



makes its density be to that of air as 2.41 is 
to 1.00; but Dr John Davy states its den- 
sity to that of air as 2.371 to 1.000. It is 
colourless ; its smell is pungent, and resem- 
bles that of muriatic acid; it cannot be 
breathed without suffocation ; it extinguishes 
combustion ; and reddens strongly the tinc- 
ture of turnsole. It has no manner of action 
on glass, but a very powerful one on vegetable 
and animal matter : it attacks them with as 
much force as concentrated sulphuric acid, 
and appears to operate on these bodies by 
the production of water; for while it carbo- 
nizes them, or evolves carbon, they may be 
touched without any risk of burning. Ex- 
posed to a high temperature, it is not decom- 
posed ; it is condensed by cold without 
changing its form. When it is put in contact 
with oxygen or air, either at a high or low 
temperature, it experiences no change, except 
seizing, at ordinary temperatures, the moisture 
which these gases contain. It becomes in 
consequence a liquid which emits extremely 
dense vapours. It operates in the same way 
with all the gases which contain hygrometric 
water. However little they may contain, it 
occasions in them very perceptible vapours. 
It may hence be employed with advantage to 
show whether or not a gas contains moisture. 

No combustible body, simple or compound, 
attacks fluoboric gas, if we except the alkaline 
metals. Potassium and sodium, with the aid 
of heat, burn in this gas almost as brilliantly 
as in oxygen. Boron and fluate of potash 
are the products of this decomposition. It 
might hence be inferred, that the metal seizes 
the oxygen of the boracic acid, sets the boron 
at liberty, and is itself oxidized and com- 
bined with the fluoric acid. According to 
Sir H. Davy's views, the fluoboric gas being 
a compound of fluorine and boron, the pot- 
assium unites to the former, giving rise to 
the fluoride of potassium, while the boron 
remains disengaged. 

Fluoborie gas is very soluble in water. Dr 
John Davy says, water can combine with 700 
times its own volume, or twice its weight at 
the ordinary temperature and pressure of the 
air. The liquid has a specific gravity of 
1.770. If a bottle containing this gas be 
uncorked under water, the liquid will rush in 
and fill it with explosive violence. Water 
saturated with this gas is limpid, fuming, and 
very caustic. By heat about one-fifth of the 
absorbed gas may be expelled ; but it is im- 
possible to abstract more. It then resembles 
concentrated sulphuric acid, and boils at a 
temperature considerably above 212. It 
afterwards condenses altogether, m strice, al- 
though it contains still a very large quantity 
of gas. It unites with the bases, forming 
salts called fluoborates, none of which has 
been applied to any use. The most impor- 
tant will be stated under the article SALT. 

The 2d part of the Phil. Transactions for 



ACID 



FULMINIC. 



1812, contains an excellent paper by Dr John 
Davy on fluosilicic and fluoboric gases, and 
the combinations of the latter with ammoniacal 
gas. When united in equal volumes, a pul- 
verulent salt is formed; a second volume of 
ammonia, however, gives a liquid compound ; 
and a third of ammonia, which is the limit of 
combination, affords still a liquid ; both of 
them curious on many accounts. " They 
are," says he, " the first salts that have been 
observed liquid at the common temperature 
of the atmosphere. And they are additional 
facts in support of the doctrine of definite 
proportions, and of the relation of volumes." 

ACID(FLUOTANTALIC). This acid 
is prepared in a similar way to the following; 
and forms, with the bases, salts called fluo- 
tantalates. 

ACID (FLUOTITANIC). When fluo- 
ric acid is poured on titanic acid, the latter 
becomes warm, even after having been previ- 
ously ignited, and dissolves completely with 
the aid of heat. Evaporated at a gentle heat 
to the consistence of syrup, the solution af- 
fords crystals, which do not redissolve com- 
pletely in water, but which are decomposed 
into two peculiar combinations, of which one 
is acidulous and soluble, and the other with 
excess of base is insoluble. The solution of 
the former, namely of the fluotitanic acid, in 
water, is analogous to the liquid fluosilicic 
acid ; it contains fluotitanic acid, and fluoric 
acid combined with water. The water may 
be replaced by other bases^ and in this way 
may be formed a series of salts which M. Ber- 
zelius calls fluotitanates. The fluotitanate 
of potash crystallizes in brilliant scales like 
boracic acid, which redissolve in water with- 
out decomposition. It consists, in 100 parts, 
of potash 38.7, titanic acid 35, and fluoric 
acid 26.3. 

ACID (FORMIC). To procure pure 
formic acid, Gehlen saturates the expressed 
liquor of ants with subcarbonate of potash, 
pours into the compound sulphated peroxide 
of iron, filters, evaporates to the consistence 
of syrup, and distils in a glass retort, with a 
sufficient quantity of sulphuric acid. The 
product which passes into the receiver is very 
sour, and without any perceptible odour of 
sulphurous acid. He then puts it in contact 
with carbonate of copper, evapprates the so- 
lution, and procures fine blue crystals, which 
he considers as formiate of copper. From 
this he extracts the pure and the most con- 
centrated acid possible, by decomposing the 
salt with two-thirds of its weight of sulphuric 
acid, aided by heat, distilling it into a recei- 
ver, and rectifying by a second distillation. 
From thirteen ounces of formiate thus treat- 
ed, he obtained more than six ounces and a 
half of pure formic acid. 

This acid has a very sour taste, and con- 
tinues liquid even at very low temperatures. 
Its specific gravity is 1 . 1 168 at 68, which is 



much denser than acetic acid ever is. Berze- 
lius finds, that the formiate of lead consists 
of 4.696 acid, and 14 oxide of lead ; and that 
the ultimate constituents of the dry acid are 
hydrogen 2.84 + carbon 32.40 + oxygen 
64.76 = 100. 

M. Dobereiner has recently succeeded 
(see Gilbert's Annales, xi. 107.) in forming 
this acid artificially. When a mixture of tar- 
taric acid, or of cream of tartar, black oxide 
of manganese, and water, is heated, a tumul- 
tuous action ensues, carbonic acid is evolved, 
and a liquid acid distils over, which, on su- 
perficial examination, was mistaken for acetic 
acid, but which now proves to be formic acid. 
This acid, mixed with concentrated sulphuric 
acid, is at common temperatures converted 
into water and carbonic oxide ; nitrate of sil- 
ver or of mercury converts it, when gently 
heated, into carbonic acid, the oxides being 
at the same time reduced to the metallic state. 
With baryta, oxide of lead, and oxide of cop- 
per, it produces compounds having all the 
properties of the genuine formiates of these 
metals. If a portion of sulphuric acid be 
employed in the above process, the tartaric 
acid is resolved entirely into carbonic acid, 
water, and formic acid ; and the product of 
the latter is much increased. The best pro- 
portions are, two parts tartaric acid, five per- 
oxide of manganese, and five sulphuric acid 
diluted with about twice its weight of water. 

M. Dobereiner finds, that when formic 
acid is decomposed by sulphuric acid, it is 
resolved into 24.3 water, and 75.7 carbonic 
oxide, in 100 parts; or of one volume of 
vapour of water, and two volumes carbonic 
oxide gas ; or two atoms carbon, three oxy- 
gen, and one hydrogen. 

ACID (FULMINIC). Put 6.5 parts 
of nitric acid, sp. gravity 1.36 or 1.38, into 
a pint matras, and a piece of coin contain- 
ing nearly 35 parts of pure silver. Pour the 
resulting solution into about 927 parts of 
strong alcohol, and heat to ebullition. On 
the appearance of turbidness, remove from 
the fire, and add by degrees an equal quantity 
of alcohol to the solution, in order to mode- 
rate the ebullition, and to cool it. Filter it 
when cold, and wash away the whole free 
acid. The fulminate of silver is now pure 
and white as snow. Dry it in a steam heat 
for two or three hours, after which it will be 
found to equal in weight the silver employed. 
A slight blow between hard bodies explodes 
it. It may be analyzed by rubbing it with 
the finger with forty times its weight of per- 
oxide of copper, and igniting the mixture in 
a glass tube. 100 parts of it, analyzed in 
this way, afforded 77.528 of oxide of silver. 
The acid associated with this oxide is the cy- 
anic. Hence the ultimate constituents are, 
in 100 parts, silver 72.187, oxygen 5.341, 
cyanogen 17.16, oxygen (combined with the 
silver) 5.312. It consists, therefore, of one 



ACID 



38 



GALLIC. 



atom oxide of silver, 14.75; 2 atoms cyano- 
gen, 6.5; 2 oxygen, 2 = 23.25. 

To prepare alkaline fulminates, chlorides 
should be used. Thus, to obtain the double 
fulminate of silver and potash, decompose the 
fulminate of silver by chloride of potassium ; 
being careful to add no more of the chloride 
than is sufficient to precipitate rather less than 
half the silver. The solution will contain the 
double fulminate. Liebeg and Gay Lussac, 
Ann. de Chim. et de Phys. xxv. 285. 

A C I D ( FUN GI C). The expressed juice 
of the boletus juglandis, boletus pseudo-ignia- 
rius, the phallus impudicus, merulius cantha- 
rellus, or the peziza nigra, being boiled to 
coagulate the albumen, then filtered, evapo- 
rated to the consistence of an extract, and 
acted on by pure alcohol, leaves a substance 
which has been called by Braconnot fungic 
acid. He dissolved that residue in water, 
added solution of acetate of lead, whence re- 
sulted fungate of lead, which he decomposed 
at a gentle heat by dilute sulphuric acid. 
The evolved fungic acid being saturated with 
ammonia, yielded a crystallized fungate of 
ammonia, which he purified by repeated so- 
lution and crystallization. From this salt, 
by acetate of lead, and thereafter sulphuric 
acid, as above detailed, he procured the pure 
fungic acid. 

It is a colourless, uncrystallizable, and de- 
liquescent mass, of a very sour taste. The 
fungates of potash and soda are uncrystalliz- 
able; that of ammonia forms regular six- 
sided prisms ; that of lime is moderately so- 
luble, and is not affected by the air ; that of 
baryta is soluble in fifteen times its weight of 
water, and crystallizes with difficulty; that 
of magnesia appears in soluble granular crys- 
tals. This acid precipitates from the acetate 
of lead a white flocculent fungate, which is 
soluble in distilled vinegar. When insulated, 
it does not affect solution of nitrate of silver j 
but the fungates decompose this salt. 

ACID (GALLIC). This acid is found 
in different vegetable substances which possess 
astringent properties, but most abundantly 
in the excrescences termed galls or nut-galls, 
whence it derives its name. It may be ob- 
tained by macerating galls in water, filtering, 
and suffering the liquor to stand exposed to 
the air. It will grow mouldy, be covered 
with a thick glutinous pellicle, abundance of 
glutinous flocks will fall down, and, in the 
course of two or three months, the sides of 
the vessel will appear covered with small 
yellowish crystals, abundance of which will 
likewise be found on the under surface of 
the supernatant pellicle. These crystals may 
be purified by solution in alcohol, and evapo- 
ration to dryness. 

M. Deyeux recommends to put the pow- 
dered galls into a glass retort, and apply heat 
slowly and cautiously; when the acid will 
rise and be condensed in the neck of the re- 



tort. This process requires great care, as, if 
the heat be carried so far as to disengage the 
oil, the crystals will be dissolved immediately. 
The crystals thus obtained are pretty large, 
laminated, and brilliant. 

M. Baruel, of the School of Medicine at 
Paris, finds that he can obtain pure gallic 
acid by pouring solution of white of egg into 
the infusion of nut-galls, till this ceases to be 
disturbed; then to evaporate the clarified 
liquid to dryness, to heat the residuum with 
alcohol, to filter the new liquid, and concen- 
trate it to the proper degree for the formation 
of gallic acid. 

Gallic acid placed on a red-hot iron burns 
with flame, and emits an aromatic smell, not 
unlike that of benzoic acid. It is soluble in 
twenty parts of cold water, and in three parts 
at a boiling heat. It is more soluble in alco- 
hol, which takes up an equal weight if heated, 
and one-fourth of its weight cold. 

It has an acido-astringent taste, and red- 
dens tincture of litmus. It does not attract 
humidity from the air. 

From the gallate of lead, Berzelius infers 
the equivalent of this acid to be 8.00. Its 
ultimate constitutents are, hydrogen 5.00 -}- 
carbon 56.64 + oxygen 38.36 = 100. 

This acid, in its combinations with the sa- 
lifiable bases, presents some remarkable phe- 
nomena. If we pour its aqueous solution by 
slow degrees into lime, baryta, or strontia 
water, there will first be formed a greenish- 
white precipitate. As the quantity of acid is 
increased, the precipitate changes to a violet 
hue, and eventually disappears. The liquid 
has then acquired a reddish tint. Among 
the salts, those only of black oxide and red 
oxide of iron are decomposed by the pure 
gallic acid. It forms a blue precipitate with 
the first, and a brown with the second. But 
when this acid is united with tannin, it de- 
composes almost all the salts of the perma- 
nent metals. 

Concentrated sulphuric acid decomposes 
and carbonizes it ; and the nitric acid con- 
verts it into malic and oxalic acids. 

United with baryta, strontia, lime, and 
magnesia, it forms salts of a dull yellow co- 
lour, which are little soluble, but more so if 
their base be in excess. With alkalis it forms 
salts that are not very soluble in general. 

Its most distinguishing characteristic is its 
great affinity for metallic oxides, so as, when 
combined with tannin, to take them from 
powerful acids. The more readily the me- 
tallic oxides part with their oxygen, the more 
they are alterable by the gallic acid. To a 
solution of gold it imparts a green hue ; and 
a brown precipitate is formed, which readily 
passes to the metallic state, and covers the 
solution with a shining golden pellicle. With 
nitric solution of silver, it produces a similar 
effect. Mercury it precipitates of an orange- 
yellow ; copper, brown ; bismuth, of a lemon 



ACID 



39 



HYDRIODIC. 



colour; lead, white; iron, black. Platina, 
zinc, tin, cobalt, and manganese, are not pre- 
cipitated by it. 

On dissolving gallic acid in ammonia, and 
placing the solution in contact with oxygen, 
M. Dobereiner found that it absorbed suffi- 
cient to convert all the hydrogen of the gallic 
acid into water. In this way the acid is con- 
verted into ulmin, which is composed of 2 
atoms carbon -j- 1 hydrogen -f- 2 oxygen. 
100 parts of gallic acid absorb 38 of oxygen 
within twenty- four hours. The solution mean- 
while becomes brown-coloured and opaque. 

Gallic acid is of extensive use in the art of 
dyeing, as it constitutes one of the principal 
ingredients in all the shades of black, and is 
employed to fix or improve several other co- 
lours. It is well known as an ingredient in 
ink. See GALLS, DYEING, INK, and SALT. 

ACID (GLAUCIC). This substance, 
considered as a new vegetable acid, accord- 
ing to Dr Runge, occurs in several species 
of the dipsacus and scabiosa. It is a brittle 
yellow mass, which reddens litmus and neu- 
tralizes ammonia. The tincture of the dry 
plant in alcohol is treated with ether, which 
throws down white flocculi. These, when 
dissolved in water, are to be precipitated by 
acetate of lead ; and the precipitate being de- 
composed by sulphuretted hydrogen, affords 
a mixture of glaucic and acetic acids. The 
latter is easily separable by a moderate heat. 

ACID (OF THE GRASSHOPPER). 
Probably a modification of the acetic acid. 

ACID(HIRCIC). This, according to M. 
Chevreul, is the product of the action of al- 
kalis on a peculiar oil, which he calls hircine, 
which he found combined with stearine and 
oleine in the fat of the goat and sheep. It 
is colourless, liquid at 32 F., emits the 
smell of acetic acid and that of the goat ; it 
reddens litmus ; is hardly soluble in water, 
but very soluble in alcohol: it forms with 
potash a deliquescent salt, with baryta one 
not very soluble in water, and with ammonia 
a salt which emits more of the goat effluvia 
than the acid itself. 

ACID (HYDRIODIC). This acid re- 
sembles the muriatic in being gaseous in its 
insulated state. If four parts of iodine be 
mixed with one of phosphorus, in a small 
glass retort, applying a gentle heat, and add- 
ing a few drops of water from time to time, 
a gas comes over, which must be received in 
the mercurial bath. Its specific gravity is 
4.4 ; 100 cubic inches, therefore, weigh 134.2 
grains. It is elastic and invisible, but has a 
smell somewhat similar to that of muriatic 
acid. Mercury after some time decomposes 
it, seizing its iodine, and leaving its hydro- 
gen, equal to one-half of the original bulk, 
at liberty. Chlorine, on the other hand, 
unites to its hydrogen, and precipitates the 
iodine. From these experiments, it evident- 
ly consists of vapour of iodine and hydrogen, 



which combine in equal volumes, without 
change of their primitive bulk. Its compo- 
sition by weight is therefore 8.61 of iodine 
-J- 0.0694 hydrogen, which is the relation 
of their gasiform densities; and if 8.61 be 
divided by 0.0694, it will give the prime of 
iodine 124 times greater than hydrogen; 
and as the prime of oxygen is eight times 
more than that of hydrogen, on dividing 
124 by 8, we have 15.5 for the prime equi- 
valent of iodine; to which if we add 0.125, 
the sum 15.625 represents the equivalent of 
hydriodic acid. The number deduced for 
iodine, from the relation of iodine to hydro- 
gen in volume, approaches very nearly to 
15.621, which was obtained in the other 
experiments of M. Gay Lussac. Hydriodic 
acid is partly decomposed at a red heat; and 
the decomposition is complete if it be mixed 
with oxygen. Water is formed, and iodine 
separated. 

M. Gay Lussac, in his admirable memoir 
on iodine and its combinations, published in 
the Ann. de Chimie, vol. xci. says, that the 
specific gravity he there gives for hydriodic 
gas, viz. 4.443, must be a little too great, for 
traces of moisture were seen in the inside of 
the bottle. In fact, if we take 15.621 as the 
prime of iodine to oxygen, whose specific 
gravity is 1.1111, and multiply one-half of 
this number by 15.621, as he does, we shall 
have a product of 8.6696, to which adding 
0.0694 for the density of hydrogen, we get 
the sum 8.7390, one-half of which is ob- 
viously the density of the hydriodic gas = 
4.3695. When the prime of iodine is taken 
at 15.5, then the density of the gas comes 
out 4.3. 

We can easily obtain an aqueous hydriodic 
acid very economically, by passing sulphuret- 
ted hydrogen gas through a mixture of water 
and iodine in a Woolfe's bottle. On heating 
the liquid obtained, the excess of sulphur flies 
off, and leaves liquid hydriodic acid. At tem- 
peratures below 262 it parts with its water, 
and becomes of a density =1.7. At 262 
the acid distils over. When exposed to the 
air, it is speedily decomposed, and iodine is 
evolved. Concentrated sulphuric and nitric 
acids also decompose it. When poured into 
a saline solution of lead, it throws down a 
fine orange precipitate. With solution of 
peroxide of mercury, it gives a red precipi- 
tate ; and with that of silver, a white pre- 
cipitate insoluble in ammonia. Hydriodic 
acid may also be formed, by passing hydro- 
gen over iodine at an elevated temperature. 

The compounds of hydriodic acid with the 
salifiable bases may be easily formed, either 
by direct combination, or by acting on the 
basis in water, with iodine. The latter mode 
is most economical. Upon a determinate 
quantity of iodine pour solution of potash or 
soda, till the liquid ceases to be coloured. 
Evaporate to dryness, and digest the dry salt 



ACID 



40 



IODIC. 



in alcohol of the specific gravity 0.810, or 
0.820. As the iodate is not soluble in this 
liquid, while the hydriodate is very soluble, the 
two salts easily separate from each other. 
After haying washed the iodate two or three 
times with alcohol, dissolve it in water, and 
neutralize it with acetic acid. Evaporate to 
dryness, and digest the dry salt in alcohol, 
to remove the acetate. After two or three 
washings, the iodate is pure. As for the alco- 
hol containing the hydriodate, distil it off, and 
then complete the neutralization of the potash, 
by means of a little hydriodic acid separately 
obtained. 

Sulphurous and muriatic acids, as well as 
sulphuretted hydrogen, produce no change 
on the hydriodates at the usual temperature 
of the air. 

Chlorine, nitric acid, and concentrated sul- 
phuric, instantly decompose them, and sepa- 
rate the iodine. 

"With solution of silver, they give a white 
precipitate insoluble in ammonia; with the 
pernitrate of mercury, a greenish-yellow pre- 
cipitate ; with corrosive sublimate, a precipi^ 
tate of a fine orange-red, very soluble in an 
excess of hydriodate ; and with nitrate of lead, 
a precipitate of an orange-yellow colour. 
They dissolve iodine, and acquire a deep red- 
dish-brown colour. 

Hydriodate of potash, or, in the dry state, 
iodide of potassium, yields crystals like sea- 
salt, which melt and sublime at a red heat. 
This salt is not changed by being heated in 
contact with air. ] 00 parts of water at 64, 
dissolve 143 of it. It consists of 15.5 iodine, 
and 5 potassium. 

Hydriodate of soda, called in the dry state 
iodide of sodium, may be obtained in pretty 
large flat rhomboidal prisms. These prisms 
unite together with larger ones, terminated in 
echellon, and striated longways, like those of 
sulphate of soda. This is a true hydriodate, 
for it contains much water of crystallization. 
It consists, when dry, of 15.5 iodine -|- 3 
sodium. 

Hydriodate of baryta crystallizes in fine 
prisms, similar to muriate of strontia. In 
its dry state it consists of 15.5 iodine -|- 8.75 
barium. 

The hydriodates of lime and strontia are 
very soluble ; and the first exceedingly deli- 
quescent. 

Hydriodate of ammonia results from the 
combination of equal volumes of ammoniacal 
and hydriodic gases; though it is usually 
prepared by saturating the liquid acid with 
ammonia. It is nearly as volatile as sal am- 
moniac; but it is more soluble and more 
deliquescent. It crystallizes in cubes. From 
this compound we may infer the prime of 
hydriodic acid, from the specific gravity of 
the hydriodic gas ; or having the prime we 
may determine the sp. gr. If we call 15.625 
its equivalent, then we have this proportion : 



As a prime of ammonia to a prime of hy- 
driodic acid, so is the density of ammoniacal 
to that of hydriodic gas. 

2.125: 15.625 : : 0.59; 43. 
This would make 100 cubic inches weigh 
exactly 132 grains. 

Hydriodate of magnesia is formed by unit- 
ing its constituents together ; it is deliques- 
cent, and crystallizes with difficulty. It is 
decomposed by a strong heat. 

Hydriodate of zinc is easily obtained, by 
putting iodine into water with an excess of 
zinc, and favouring their action by heat. 
When dried it becomes an iodide. 

All the hydriodates have the property of 
dissolving abundance of iodine ; and thence 
they acquire a deep reddish-brown colour. 
They part with it on boiling, or when expos- 
ed to the air after being dried. See SALT. 

ACID (IODIC). When baryta water is 
made to act on iodine, a soluble hydriodate, 
and an insoluble iodate of baryta, are formed, 
On the latter, well washed, pour sulphuric 
acid equivalent to the baryta present, diluted 
with twice its weight of water, and heat the 
mixture. The iodic acid quickly abandons 
a portion of its base, and combines with the 
water ; but though even less than the equi- 
valent proportion of sulphuric acid has been 
used, a little of it will be found mixed with 
the liquid acid. If we endeavour to separate 
this portion, by adding baryta water, the two 
acids precipitate together. 

The above economical process is that of 
M. Gay Lussac; but Sir H. Davy, who is the 
discoverer of this acid in a solid state, invented 
one which yields a purer acid. Into a long 
glass tube, bent like the letter L inverted (l), 
shut at one end, put 100 grains of chlorate 
of potash, and pour over it 400 grains of 
muriatic acid, specific gravity 1.105. Put 
40 grains of iodine into a thin long-necked 
receiver. Into the open end of the bent tube 
put some muriate of lime, and then connect 
it with the receiver. Apply a gentle heat to 
the sealed end of the former. Protoxide of 
chlorine is evolved, which, as it comes in con- 
tact with the iodine, produces combustion, and 
two new Compounds a compound of iodine 
and oxygen, and one of iodine and chlorine. 
The latter is easily separable by heat, while 
the former remains in a state of purity. 

The iodic acid of Sir H. Davy is a white 
semitransparent solid. It has a strong aci- 
do-astringent taste, but no smell. Its den- 
sity is considerably greater than that of sul- 
phuric acid, in which it rapidly sinks. It 
melts, and is decomposed into iodine and 
oxygen, at a temperature of about 620. A 
grain of iodic acid gives out 176.1 grain 
measures of oxygen gas. It would appear 
from this, that iodic acid consists of 15.5 
iodine to 5 oxygen. This agrees with the 
determination of M. Gay Lussac, obtained 
from much greater quantities ; and must 



ACID 



4.1 



CHLORIODIC. 



therefore excite admiration at the precision 
of result derived by Sir H. from the very 
minute proportions which he used. 176.1 
grain measures are equal to 0.7 of a cubic 
inch ; which, calling 100 cubic inches 33.88, 
will weigh 0.237 of a grain, leaving 0.763 for 
iodine. And 0.763 : 0.237 : : 15.5 : 5.0. 

lodic acid deliquesces in the air, and is, of 
course, very soluble in water. It first reddens 
and then destroys the blues of vegetable in- 
fusions. It blanches other vegetable co- 
lours. By concentration of the liquid acid 
of Gay Lussac, it acquires the consistence of 
syrup. When the temperature of inspissated 
iodic acid is raised to about 392, it is resolv- 
ed into iodine and oxygen. Here we see 
the influence of water is exactly the reverse 
of what M. Gay Lussac assigns to it; for, 
instead of giving fixity like a base to the acid, 
it favours its decomposition. The dry acid 
may be raised to upwards of 600 without 
being decomposed. Sulphurous acid, and 
sulphuretted hydrogen, immediately separate 
iodine from it. Sulphuric and nitric acids 
have no action on it. With solution of silver 
it gives a white precipitate, very soluble in 
ammonia. It combines with all the bases, 
and produces all the iodates which we can 
obtain by making the alkaline bases act upon 
iodine in water. It likewise forms with am- 
monia a salt, which fulminates when heated. 
Between the acid prepared by M. Gay Lus- 
sac and that of Sir H. Davy, there is one im- 
portant difference. The latter being dissol- 
ved may, by evaporation of the water, pass 
not only to the inspissated syrupy state, but 
can be made to assume a pasty consistence ; 
and finally, by a stronger heat, yields the 
solid substance unaltered. When a mixture 
of it, with charcoal, sulphur, resin, sugar, or 
the combustible metals, in a finely divided 
state, is heated, detonations are produced; 
and its solution rapidly corrodes all the 
metals to which Sir H. Davy exposed it, both 
gold and platinum, but much more intensely 
the first of these metals. 

It appears to form combinations with all 
the fluid or solid acids which it does not de- 
compose. When sulphuric acid is dropped 
into a concentrated solution of it in hot water, 
a solid substance is precipitated, which con- 
sists of the acid and the compound ; for, on 
evaporating the solution by a gentle heat, 
nothing rises but water. On increasing the 
heat in an experiment of this kind, the solid 
substance formed fused ; and, on cooling the 
mixture, rhomboidal crystals formed of a 
pale yellow colour, which were very fusible, 
and which did not change at the heat at 
which the compound of oxygen and iodine 
decomposes, but sublimed unaltered. When 
urged by a much stronger heat, it partially 
sublimed, and partially decomposed, afford- 
ing oxygen, iodine, and sulphuric acid. 

With phosphoric acid, the compound pre- 



sents phenomena precisely similar, and they 
form together a solid, yellow, crystalline 
combination. 

With liquid nitric acid it yields white crys- 
tals in rhomboidal plates, which, at a lower 
heat than the preceding acid compounds, 
are resolved into liquid nitric acid, oxygen, 
and iodine. By liquid muriatic acid the sub- 
stance is immediately decomposed, and the 
compound of chlorine and iodine is form- 
ed. All these acid compounds redden veget- 
able blues, taste sour, and dissolve gold and 
platinum. From these curious researches Sir 
H. Davy infers, that M. Gay Lussac's iodic 
acid is a sulpho-iodic acid, and probably a 
definite compound. However minute the 
quantity of sulphuric acid made to act on the 
iodide of barium may be, a part of it is always 
employed to form the compound acid ; and 
the residual fluid contains both the compound 
acid and a certain quantity of the original salt. 

In treating of hydriodic acid, we have al- 
ready described the method of forming the 
iodates, a class of salts distinguished chiefly 
by their property of deflagrating when heated 
with combustibles. See SALT. 

ACID(IODOUS). Equal parts of chlo- 
rate of potash and iodine are to be triturated 
together in a glass or porcelain mortar, until 
they form a fine pulverulent yellow mass, in 
which the metallic aspect of the iodine has en- 
tirely disappeared. This mixture is to be put 
into a retort, the neck being preserved clean, 
and a receiver is to be attached with a tube 
passing to the pneumatic trough. Heat is 
then to be applied ; and for this purpose a 
spirit lamp will be sufficient. At first a few 
violet vapours rise, but as soon as the chlorate 
begins to lose oxygen, dense yellow fumes 
will appear, which will be condensed in the 
neck of the retort into a yellow liquid, and 
run in drops into the receiver ; oxygen gas 
will at the same time come over. When the 
vapour ceases to rise, the process is finished, 
and the iodous acid obtained will have the 
following properties: 

Its colour is yellow; taste acid and astrin- 
gent, leaving a burning sensation on the 
tongue. It is of an oily consistency, and 
flows with difficulty. It is denser than water. 
Its odour somewhat resembles that of eu- 
chlorine. It reddens vegetable blues, but 
does not destroy them. At 112 F. it vola- 
tilizes rapidly in dense fumes. It dissolves 
iodine, and assumes a deep colour. Semen- 
tini, Bib. Univ. xxv. 119. 

M. Pleischl says, that, in preparing this 
acid, three parts of chlorate of potash with 
one of iodine are to be used, and not equal 
parts, as prescribed by Sementini. It is in- 
dispensable to cool the receiver considerably 
during the whole operation. 

ACID (CHLORIODIC). The disco- 
very of this interesting compound constitutes 
another of Sir H. Davy's contributions to 



ACID 



42 



HYDROCYANIC. 



the advancement of science. In a commu- 
nication from Florence to the Royal Society, 
in March 1814, he gives a curious detail of 
its preparation and properties. He formed 
it by admitting chlorine in excess to known 
quantities of iodine, in vessels exhausted of 
air, and repeatedly heating the sublimate. 
Operating in this way, he found that iodine 
absorbs less than one-third of its weight of 
chlorine. 

Chloriodic acid is a very volatile substance, 
and, in consequence of its action upon mer- 
cury, he was not able to determine the elastic 
force of its vapours. In the most considerable 
experiment which he made to determine pro- 
portions, 20 grains caused the disappearance 
of 9. 6 cubical inches of chlorine. These weigh 
7.296 grains. And 20 : 7.296 :: 15.5 : 5.6, 
a number not very far from 4.5, the prime 
equivalent of chlorine ; and, in the delicate 
circumstances of the experiment, an approxi- 
mation not to be disparaged. Indeed, the 
first result in close vessels, giving less than 
one-third of the weight of chlorine absorbed, 
comes sufficiently near 4.5, which is just a 
little less than one-third of 15.5, the prime 
equivalent of iodine. 

The chloriodic acid formed by the sublima- 
tion of iodine in a great excess of chlorine is 
of a bright yellow colour ; when fused, it be- 
comes of a deep orange, and when rendered 
elastic, it forms a deep orange-coloured gas. 
It is capable of combining with much iodine 
when they are heated together: its colour 
becomes, in consequence, deeper, and the 
chloriodic acid and the iodine rise together in 
the elastic state. The solution of the chlo- 
riodic acid in water likewise dissolves large 
quantities of iodine, so that it is possible to 
obtain a fluid containing very different pro- 
portions of iodine and chlorine. 

When two bodies so similar in their cha- 
racters, and in the compounds they form, as 
iodine and chlorine, act upon substances at 
the same time, it is difficult, Sir H. observes, 
to form a judgment of the different parts that 
they play iu the new chemical arrangement 
produced. It appears most probable, that 
the acid property of the chloriodic compound 
depends upon the combination of the two 
bodies ; and its action upon solutions of the 
alkalis and the earths may be easily explained, 
when it is considered that chlorine has a 
greater tendency than iodine to form double 
compounds with the metals, and that iodine 
has a greater tendency than chlorine to form 
triple compounds with oxygen and the metals. 

A triple compound of this kind with so- 
dium may exist in sea water, and would be 
separated with the first crystals that are 
formed by its evaporation. Hence, it may 
exist in common salt. Sir H. Davy ascer- 
tained, by feeding birds with bread soaked 
with water holding some of it in solution, 
that it is not poisonous like iodine itself. 



ACID (HYDROBROMIC). Put bro- 
mine and phosphorus in contact, and moisten 
them with a few drops of water : A gaseous 
matter is evolved, which may be collected 
over mercury, and which is hydrobromic acid. 
It is colourless. Taste acid. It diffuses in 
the air white vapours, denser than those of 
muriatic acid in the same circumstances, and 
which excite coughing. This gas is not de- 
composed by traversing an ignited tube, either 
alone or mixed with oxygen. It is instantly 
decomposed by chlorine, which, seizing the 
hydrogen, produces immediately abundant 
ruddy vapours, and a deposit of bromine in 
small drops. Tin and potassium also decom- 
poses hydrobromic acid, and one-half of its 
volume of hydrogen remains. This gaseous 
acid combines readily with water. The solu- 
tion is colourless when rightly prepared ; but 
excess of bromine gives it a deep ruddy hue. 
Iron, zinc, and tin, dissolve in the liquid acid, 
with disengagement of hydrogen Bromine 
has for hydrogen a weaker affinity than chlo- 
rine has, but a stronger than iodine. 

As the prime equivalent of bromine is in- 
ferred from the bromide of potassium to be 
about 9.5, that of hydrobromic acid should 
be 9.625, or 77 times the weight of the prime 
of hydrogen. Balard, Annales de Chim. et 
de Phys. xxxii. 347. 

ACID (HYDROCYANIC). To a quan- 
tity of powdered prussian blue, diffused in 
boiling water, let red oxide of mercury be 
added in successive portions till the blue co- 
lour is destroyed. Filter the liquid, and con- 
centrate by evaporation till a pellicle appears. 
On cooling, crystals of prussiate or cyanide 
of mercury will be formed. Dry these, and 
put them into a tubulated glass retort, to the 
beak of which is adapted a horizontal tube 
about two feet long, and fully half an inch 
wide at its middle part. The first third part 
of the tube next the retort is filled with small 
pieces of white marble, the two other thirds 
with fused muriate of lime. To the end of 
this tube is adapted a small receiver, which 
should be artificially refrigerated. Pour on 
the crystals muratic acid, in rather less quan- 
tity than is sufficient to saturate the oxide of 
mercury which formed them. Apply a very 
gentle heat to the retort. Hydrocyanic acid 
will be evolved in vapour, and will condense 
in the tube. Whatever muriatic acid may 
pass over with it, will be abstracted by the 
marble, while the water will be absorbed by 
the muriate of lime. By means of a mode- 
rate heat applied to the tube, the prussic acid 
may be made to pass successively along ; and 
after being left some time in contact with the 
muriate of lime, it may be finally driven into 
the receiver. As the carbonic acid evolved 
from marble by the muriatic is apt to carry 
off some of the prussic acid, care should be 
taken to conduct the heat so as to prevent 
the distillation of this mineral acid. 



ACID 



43 



HYDROCYANIC. 



Hydrocyanic acid thus obtained has the 
following properties. It is a colourless li- 
quid, possessing a strong odour ; and the 
exhalation, if incautiously snuffed up the 
nostrils, may produce sickness or fainting. 
Its taste is cooling at first, then hot, asthenic 
in a high degree, and a true poison. Its 
specific gravity at 44J, is 0.7058; at 64 
it is 0.6969. It boils at 81^, and congeals 
at about 3. It then crystallizes regularly, 
and affects sometimes the fibrous form of 
nitrate of ammonia. The cold which it pro- 
duces, when reduced into vapour, even at the 
temperature of 68, is sufficient to congeal 
it. This phenomenon is easily produced by 
putting a small drop at the end of a slip of 
paper or a glass tube. Though repeatedly 
rectified on pounded marble, it retains the 
property of feebly reddening paper tinged 
blue with litmus. The red colour disappears 
as the acid evaporates. 

The specific gravity of its vapour, experi- 
mentally compared to that of air, is 0.9476. 
By calculation from its constituents, its true 
specific gravity comes out 0.9360, which dif- 
fers from the preceding number by only one- 
hundredth part. This small density of prus- 
sic acid, compared with its great volatility, 
furnishes a new proof that the density of 
vapours does not depend upon the boiling 
point of the liquids that furnish them, but 
upon their peculiar constitution. 

M. Gay Lussac analyzed this acid by in- 
troducing its vapour, at the temperature of 
86, into a jar two-thirds filled with oxygen, 
over warm mercury. When the temperature 
of the mercury was reduced to that of the 
ambient air, a determinate volume of the 
gaseous mixture was taken and washed in a 
solution of potash, which abstracts the prussic 
acid, and leaves the oxygen. This gaseous 
mixture may, after this inspection, be em- 
ployed without any chance that the hydro- 
cyanic acid will condense, provided the tem- 
perature be not too low ; but during M. Gay 
Lussac's experiments it was never under 
7H. A known volume was introduced 
into a Volta's eudiometer, with platina wires, 
and an electric spark was passed across the 
gaseous mixture. The combustion is lively, 
and of a bluish-white colour. A white prus- 
sic vapour is seen, and a diminution of vo- 
lume takes place, which is ascertained by 
measuring the residue in a graduated tube. 
This being washed with a solution of potash 
or baryta, suffers a new diminution from the 
absorption of the carbonic acid gas formed. 
Lastly, the gas which the alkali has left is 
analyzed over water by hydrogen, and it is 
ascertained to be a mixture of nitrogen and 
oxygen, because this last gas was employed 
in excess. 

The following are the results, referred to 
hydrocyanic acid vapour : 



Vapour, - - - 100 

Diminution after combustion, 78.5 

Carbonic acid gas produced, 101.0 

Nitrogen, - 46.0 

Hydrogen, - 55.0 

During the combustion a quantity of oxy- 
gen disappears, equal to about 1^ of the va- 
pour employed. The carbonic acid produced 
represents one volume, and the other fourth 
is supposed to be employed in forming wa- 
ter ; for it is impossible to doubt that hydro- 
gen enters into the composition of prussic 
acid. From the laws of chemical proportions 
M. Gay Lussac concludes, that hydrocyanic 
acid vapour contains just as much carbon as 
will form its own bulk of carbonic acid, half 
a volume of nitrogen, and half a volume of 
hydrogen. This result is evident for the car- 
bon ; and though, instead of 50 of nitrogen 
and hydrogen, which ought to be the num- 
bers according to the supposition, he obtained 
46 for the first, and 55 for the second, he 
ascribes the discrepancy to a portion of the 
nitrogen having combined with the oxygen 
to form nitric acid. 

The density of carbonic acid gas being, 
according to M. Gay Lussac, 1.5196, and 
that of oxygen 1. 1036, the density of the va- 
pour of carbon is 1.51961.1036=0.4160. 
Hence, 1 volume carbon =0.4160 

Half a volume of hydrogen = 0.0366 
Half a volume of nitrogen = 0.4845 

Sum = 0.9371 

Thus, according to the analytical state- 
ment, the density of prussic vapour is 0.9371, 
and by direct experiment it was found to be 
0.9476. It may therefore be inferred from 
this near coincidence, that prussic acid va- 
pour contains one volume of the vapour of 
carbon, half a volume of nitrogen, and half a 
volume of hydrogen, condensed into one 
volume, and that no other substance enters 
into its composition. 

M. Gay Lussac confirmed the above de- 
termination, analyzing hydrocyanic acid by 
passing its vapour through an ignited porce- 
lain tube containing a coil of fine iron wire, 
which facilitates the decomposition of this 
vapour, as it does with ammonia. No trace 
of oxygen could be found in prussic acid. 
And again, by transmitting the acid in va- 
pour over ignited peroxide of copper in a 
porcelain tube, he came to the same conclu- 
sion with regard to its constituents. They 
are, 

One volume of the vapour of carbon, 
Half a volume of hydrogen, 
Half a volume of nitrogen, 
condensed into one volume; or, in weight, 
Carbon, - 44.39 

Nitrogen, - - 51.71 

Hydrogen, - 3.90 

100.00 



ACID 



44 



HYDROCYANIC. 



This acid, when compared with the other 
animal products, is distinguished by the great 
quantity of nitrogen it contains, by its small 
quantity of hydrogen, and especially by the 
absence of oxygen. 

When this strong acid is kept in well- 
closed vessels, even though no air be present, 
it is sometimes decomposed in less than an 
hour. It has been occasionally kept fifteen 
days without alteration ; but it is seldom that 
it can be kept so long, without exhibiting 
signs of decomposition. It begins by assum- 
ing a reddish-brown colour, which becomes 
deeper and deeper, and it gradually deposits 
a considerable carbonaceous matter, which 
gives a deep colour to both water and acids, 
and emits a strong smell of ammonia. If 
the bottle containing the prussic acid be not 
hermetically sealed, nothing remains but a 
dry charry mass, which gives no colour to 
water. Thus a hydrocyanate of ammonia is 
formed at the expense of a part of the acid, 
and an azoturet of carbon. When potassium 
is heated in hydrocyanic acid vapour, mixed 
with hydrogen or nitrogen, there is absorption 
without inflammation, and the metal is con- 
verted into a grey spongy substance, which 
melts, and assumes a yellow colour. 

Supposing the quantity of potassium em- 
ployed capable of disengaging from water a 
volume of hydrogen equal to 50 parts, we 
find after the action of the potassium, 

1. That the gaseous mixture has expe- 
rienced a diminution of volume amounting 
to 50 parts : 2. On treating this mixture with 
potash, and analyzing the residue by oxygen, 
that 50 parts of hydrogen have been pro- 
duced : 3. And consequently that the potas- 
sium has absorbed 100 parts of prussic va- 
pour ; for there is a diminution of 50 parts, 
which would obviously have been twice as 
great had not 50 parts of hydrogen been 
disengaged. The yellow matter is prussiate 
of potash ; properly a cyanide of potassium, 
analogous in its formation to the chloride 
and iodide, when muriatic and hydriodic 
gases are made to act on potassium. 

The base of hydrocyanic acid thus divested 
of its acidifying hydrogen, might be called, 
agreeably to the old chemical analogy, prus- 
sine. M. Gay Lussac styles it cyanogen, be- 
cause it is the principle which generates blue ; 
or literally, the blue-maker. 

Like muriatic and hydriodic acids, this 
acid contains half its volume of hydrogen. 
The only difference is, that the former have, 
in the present state of our knowledge, simple 
radicals, chlorine and iodine ; while that of 
the latter is a compound of one volume 
vapour of carbon, and half a volume of nitro- 
gen. This radical forms true cyanides with 
metals. 

The cyanide of potassium gives a very al- 
kaline solution in water, even when a great 
excess of hydrocyanic vapour has been pre- 



sent at its formation. In this respect it dif- 
fers from the chlorides and iodides of that 
metal, which are perfectly neutral. Know- 
ing the composition of prussic acid, and that 
potassium separates from it as much hydro- 
gen as from water, it is easy to find its pro- 
portional number or equivalent to oxygen. 
We must take such a quantity of prussic acid 
that its hydrogen may saturate 10 of oxygen. 
Thus we find the prime equivalent of this 
acid to be 33.846; and, subtracting the 
weight of hydrogen, there remains 32.52 for 
the equivalent of the cyanogen itself. But 
if we reduce the numbers representing the 
volumes to the prime equivalents adopted in 
this Dictionary, viz. 0.75 for carbon, 0.125 
for hydrogen, and 1.75 for nitrogen, we shall 
have the relation of volumes slightly modi- 
fied. Since the fundamental combining ratio 
of oxygen to hydrogen in bulk is \ to 1, we 
must multiply the prime equivalent by half 
the specific gravity of oxygen, and we obtain 
the following numbers : 
1 volume car. =0.75 X 0.5555=0.41663 



| volume hyd.: 
i volume nitr.: 



0.125x0.5555 



2 
1.75 X 0.5555 



= 0.03471 



: 0.48610 



Sum =0.93744 

Or, as is obvious by the above calculation, 
we may take 2 primes of carbon, 1 of hydro- 
gen, and 1 of nitrogen, which directly added 
together will give the same results, since by 
so doing we merely take away the common 
multiplier 0.5555. Thus we have 

2 primes carbon, - 1.500 

1 prime hydrogen, - - 0. 1 25 
1 prime nitrogen, - '* 1.750 

3.375 

Which, reduced to proportions per cent, give 

of Carbon, - - - 44.444 

Hydrogen, -* 3.737 

Nitrogen, - 51.818 

100.000 

Baryta, potash, and soda, combine with 
cyanogen, forming true cyanides of these 
alkaline oxides, analogous to what are vul- 
garly called oxymuriates of lime, potash, and 
soda. The red oxide of mercury acts so 
powerfully on hydrocyanic acid vapour, when 
assisted by heat, that the compound which 
ought to result is destroyed by the heat dis- 
engaged. The same thing happens when a 
little of the concentrated acid is poured upon 
the oxide. A great elevation of temperature 
takes place, which would occasion a danger- 
ous explosion if the experiment were made 
upon considerable quantities. When the 
acid is diluted, the oxide dissolves rapidly, 
with a considerable heat, and without the 
disengagement of any gas. The substance 
formerly called prussiate of mercury is gene- 
rated, which when moist may, like the muri- 



ACID 



HYDROCYANIC. 



ates, be deemed a hydrocyanate ; but when 
dry, is a cyanide of the metal. 

When the cold oxide is placed in contact 
with the acid, dilated into a gaseous form by 
hydrogen, its vapour is absorbed in a few mi- 
nutes. The hydrogen is unchanged. When 
a considerable quantity of vapour has thus 
been absorbed, the oxide adheres to the side 
of the tube, and, on applying heat, water is 
obtained. The hydrogen of the acid has 
here united with the oxygen of the oxide to 
form the water, while their two radicals com- 
bine. Red oxide of mercury becomes an 
excellent reagent for detecting prussic acid. 
By exposing the dry cyanide of mercury 
to heat in a retort, the radical cyanogen is 
obtained. See CYANOGEN. 

On subjecting hydrocyanic acid to the ac- 
tion of a battery of 20 pairs of plates, much 
hydrogen is disengaged at the negative pole, 
and cyanogen at the positive, which remains 
dissolved in the acid. Since potash by heat 
separates the hydrogen of the prussic acid, 
we see that in exposing a mixture of potash 
and animal matters to a high temperature, a 
true cyanide of potash is obtained, formerly 
called the prussian or phlogisticated alkali. 
When cyanide of potassium is dissolved in 
water, hydrocyanate of potash is produced, 
which is decomposed by the acids without 
generating ammonia or carbonic acid : but 
when cyanide of potash dissolves in water, 
no change takes place ; and neither ammo- 
nia, carbonic acid, nor hydrocyanic vapour is 
given out, unless an acid be added. These 
are the characters which distinguish a metal- 
lic cyanide from the cyanide of an oxide. 

From the experiments of M. Magendie it 
appears, that the pure hydrocyanic acid is the 
most violent of all poisons. When a rod 
dipped into it is brought in contact with the 
tongue of an animal, death ensues before the 
rod can be withdrawn. If a bird be held a 
moment over the mouth of a phial contain- 
ing this acid, it dies. In the Annales de 
Chimie for 1814 we find this notice : M. B. 
professor of chemistry, left by accident on a 
table a flask containing alcohol impregnated 
with prussic acid ; the servant, enticed by the 
agreeable flavour of the liquid, swallowed a 
small glass of it. In two minutes she drop- 
ped down dead, as if struck with apoplexy. 
The body was not examined. 

" Scharinger, a professor at Vienna," says 
Orfila, " prepared six or seven months ago a 
pure and concentrated prussic acid ; he spread 
a certain quantity of it on his naked arm, 
and died a little time thereafter." 

Dr Magendie has, however, ventured to 
introduce its employment into medicine. He 
found it beneficial against phthisis and chro- 
nic catarrhs. His formula is the following : 
Mix one part of the pure hydrocyanic 
acid of M. Gay Lussac with 8J of water by 
weight. To this mixture he gives the name 
of medicinal prussic acid. 



Of this he takes 1 gros. or 59 gr. Troy, 

Distilled water, 1 Ib. or 7560 gr. 

Pure sugar, J oz. or 708f gr. 
and, mixing the ingredients well together, 
he administers a table-spoonful every morn- 
ing and evening. 

The simplest, and perhaps most economi- 
cal process which I know for obtaining hy- 
drocyanic acid of moderate strength, for most 
chemical, and all medical purposes, is to dis- 
solve ferrocyanate of potash in water, and to 
add to the solution, contained in a retort, as 
much sulphuric -acid as there was salt em- 
ployed. Distilling with a gentle heat, hy- 
drocyanic acid is obtained. If it be tinged 
blue with a little iron, this may be separated 
either by filtration or redistillation. Another 
mode which I have found to afford an acid 
which keeps well, is to transmit a current of 
sulphuretted hydrogen gas through a solution 
of cyanide of mercury, till the whole metal 
be separated in the state of sulphuret. This 
subsides, and leaves liquid hydrocyanic acid 
mixed with some sulphuretted hydrogen, 
which may be removed by agitation with 
carbonate of lead. This is merely a modi- 
fication of Vauquelin's original process, in 
which sulphuretted hydrogen gas was made 
to act on the solid cyanide of mercury con- 
tained in a glass tube. 

Hydrocyanic acid is formed in a great 
many chemical operations; as for instance, 
by transmitting ammoniacal gas over ignited 
charcoal contained in a tube ; as also, by 
heating in a glass tube, closed at one end, a 
mixture of oxalate of ammonia and oxalate 
of manganese. Formiate of ammonia de- 
composed in a glass retort, is converted into 
hydrocyanic acid and water. 

One ten-thousandth part of hydrocyanic 
acid may be detected in water, by the addi- 
tion of a few drops of solution of sulphate of 
iron. This test, although delicate, is surpass- 
ed by another, in which copper is used, and 
which will detect 50.^00 of hydrocyanic acid 
in water. We must render the liquid con- 
taining the hydrocyanic acid slightly alkaline 
with potash ; add a few drops of sulphate of 
copper, and afterwards sufficient muriatic 
acid to redissolve the excess of oxide of cop- 
per. The liquid will appear more or less 
milky, according to the quantity of hydro- 
cyanic acid present. 

A cat was poisoned by twelve drops of 
hydrocyanic acid in sixty drops of water : 
the animal died one minute after having 
swallowed the poison. At the moment of 
its death, a vapour came from its throat 
smelling strongly of the acid, and a paper 
moistened with alkali, when held to it, was 
afterwards rendered blue by persulphate of 
iron. The animal was kept at the tem- 
perature of 50 F. for eighteen hours, and 
then opened. The odour of prussic acid was 
readily perceived in the brain, spinal marrow, 



ACID 



46 



HYDROCYANIC. 



and thoracic organs. It was but slightly 
perceptible in the stomach, which contained 
nothing but mucus ; but on cutting the or- 
gan in pieces, it was developed. The sto- 
mach was cut into pieces under water, and 
distilled with the water. When about an 
eighth of the liquid had passed over, it was 
mixed with potash and persulphate of iron, 
and soon gave a feeble blue tint, leaving no 
doubt of the presence of hydrocyanic acid. 
The test by copper gave it still more sensi- 
bly. The copper detected prussic acid also 
in the intestines ; but the persulphate of iron 
did not. Aqueous chlorine has been found to 
be an antidote to the poison of prussic acid. 

Having been consulted by physicians and 
apothecaries concerning the strength of the 
dilute hydrocyanic acid employed in medi- 
cine, I instituted a series of experiments to 
determine the relation between its specific 
gravity and quantity of real acid. The acid 
which I prepared with this view had a speci- 
fic gravity = 0. 957. 

The following Table comprehends their 
results. 



Quantity of above 
Liquid Acid. 

100.0 
66.6 
57.0 
50.0 
44.4, 
4-0.0 
36.4 
33.3 
30.8 
28.6 
25.0 
22.2 
20.0 
18.2 
16.6 
15.4 
14.3 
13.3 
12.5 
11.8 
10.5 
10.0 



Sp. Gravity. 

0.9570 
0.9768 
0.9815 
0.9840 
0.9870 
0.9890 
0.9900 
0.9914 
0.9923 
0.9930 
0.9940 
0.9945 
0.9952 
0.9958 
0.9964 
0.9967 
0.9970 
0.9973 
0.9974 
0.9975 
0.9978 
0.9979 



Real Acid 
per cent 

16 
10.6 

9.1 

8.0 

7.3 

6.4 

5.8 

5.3 

5.0 

4.6 

4.0 

3.6 

3.2 

3.0 

2.7 

2.5 

2.3 

2.1 

2.0 

1.77 

1.68 

1.60 



From the preceding table it i* obvious, 
that for acid of specific gravity 0.996 or 
0.997, such as is usually prescribed in medi- 
cine, the density is a criterion of greater 
nicety than can be conveniently used by the 
majority of practitioners. In fact, the liquid 
at 0.996 contains about double the quantity 
of real acid which it does at 0.998. It is 
therefore desirable to have another test of the 
strength of this powerful and dangerous me- 
dicine, which shall be easier in use, and more 
delicate in its indications. Such a test is 
afforded by the red oxide of mercury, the 
common red precipitate of the shops. The 



prime equivalent of prussic acid is exactly 
one-eighth of that of the mercurial peroxide. 
But as the prussiate of mercury consists of 
two primes of acid- to one of base, or is, in 
its dry crystalline state, a bicyanide, we have 
the relation of one to four in the formation 
of that salt, when we act on the peroxide 
with cold prussic acid. Hence we derive 
the following simple rule of analysis. To 
100 grains, or any other convenient quantity 
of the acid, contained in a small phial, add 
in succession small quantities of the peroxide 
of mercury in fine powder, till it ceases to be 
dissolved on agitation. The weight of the 
red precipitate taken up being divided by 
four, gives a quotient representing the quan- 
tity of real prussic acid present. By weigh- 
ing out beforehand, on a piece of paper or 
a watch-glass, forty or fifty grains of the per- 
oxide, the residual weight of it shows at once 
the quantity expended. 

The operation may be always completed 
in five minutes, for the red precipitate dis- 
solves as rapidly in the dilute prussic acid, 
with the aid of slight agitation, as sugar 
dissolves in water. Should the presence of 
muriatic acid be suspected, then the specific 
gravity of the liquid being compared with the 
numbers in the above table, and with the 
weight of peroxide dissolved, will show how 
far the suspicion is well founded. Thus, 
if 100 grains of acid, specific gravity 0.996, 
dissolve more than 12 grains of the red pre- 
cipitate, we may be sure that the liquid has 
been contaminated with muriatic acid. Ni- 
trate of silver, in common cases so valuable 
a reagent for muriatic acid, is unfortunately 
of little use here ; for it gives with prussic 
acid a flocculent white precipitate, soluble in 
water of ammonia, and insoluble in nitric 
acid, which may be easily mistaken by com- 
mon observers for the chloride of that metal. 
But the difference in the volatility of prus- 
siate and muriate of ammonia may be had 
recourse to with advantage ; the former ex- 
haling at a very gentle heat, the latter requir- 
ing a subliming temperature of about 300 
Fahrenheit. After adding ammonia in slight 
excess to the prussic acid, if we evaporate to 
dryness at a heat of 212, we may infer from 
the residuary sal ammoniac the quantity of 
muriatic acid present. 

The preceding table is the result of experi- 
ments which I made some time ago at Glas- 
gow. I have lately verified its accuracy by 
experiments made at the Apothecaries' Hall, 
London, on their pure prussic acid. 100 
grains of the bicyanide of mercury require 
for their conversion into bichloride (corrosive 
sublimate), 28.56 grains of chlorine, a quan- 
tity to be found in 100 grains of muriatic 
acid, specific gravity 1.1452. And as 100 
grains of the bicyanide afford 20.6 of real 
prussic acid, they will furnish, by careful dis- 
tillation on a water bath, a quantity of liquid 



ACID 



47 



CYANIC. 



acid, equivalent to 700 grains of the medici- 
nal strength 0.996. By consulting my table 
of muriatic acid, published in this Diction- 
ary, the quantity of it at any density, neces- 
sary for decomposing the above cyanide, will 
be immediately found; bearing in mind, 
that 31.5, = the prime equivalent of the 
salt, corresponds to 9 of chlorine. 

Scheele found that prussic acid occasioned 
precipitates with only the following three 
metallic solutions ; nitrates of silver, and 
mercury, and carbonate of silver. The first 
is white, the second black, the third green, 
becoming blue. 

The hydrocyanates are all alkaline, even 
when a great excess of acid is employed in 
their formation ; and they are decomposed by 
the weakest acids. 

The hydrocyanate of ammonia crystallizes 
in cubes, in small prisms crossing each other, 
or in feathery crystals, like the leaves of a 
fern. Its volatility is such, that at the tem- 
perature of 71f it is capable of bearing a 
pressure of 17.72 inches of mercury; and at 
97 its elasticity is equal to that of the atmo- 
sphere. Unfortunately this salt is charred 
and decomposed with extreme facility. Its 
great volatility prevented M. Gay Lussac 
from determining the proportion of its con- 
stituents. Hydrocyanic acid converts iron 
or its oxide into prussian blue, without the 
help either of alkalis or acids. Cyanogen 
acts on iron and water as iodine does on 
water and a base ; and a CYANIC acid is 
formed, which dissolves a part of the iron, 
but also and at the same time hydrocyanic 
acid, which changes another part of the iron 
into prussian blue. 

According to M. Vauquelin, very complex 
changes take place when gaseous cyanogen is 
combined with water, which leave the nature 
of the above acid involved in some obscurity. 
The water is decomposed : part of its hydro- 
gen combines with one part of the cyanogen, 
and forms hydrocyanic acid ; another part 
unites with the nitrogen of the cyanogen, 
and forms ammonia ; and the oxygen of the 
water forms carbonic acid, with one part of 
the carbon of the cyanogen. Hydrocyanate, 
carbonate, and cyanate of ammonia, are also 
found in the liquid ; and there still remain 
some carbon and nitrogen, which produce 
a brown deposit. Four and a half parts of 
water absorb one of gaseous cyanogen, which 
communicate to it a sharp taste and smell, 
but no colour. The solution in the course 
of some days, however, becomes yellow, and 
afterwards brown, in consequence of the 
intestine changes related above. 

Hydrocyanic acid is separated from potash 
by carbonic acid ; but when oxide of iron is 
added to the potash, M. Gay Lussac conceives 
that a triple compound, united by a much 
more energetic affinity, results, constituting 
what is usually called prussiate of potash, or 



prussiate of potash and iron. In illustration 
of this view, he prepared a hydrocyanate of 
potash and silver, which was quite neutral, 
and which crystallized in hexagonal plates. 
The solution of these crystals precipitates 
salts of iron and copper white. Muriate 
of ammonia does not render it turbid ; but 
muriatic acid, by disengaging hydrocyanic 
acid, precipitates chloride of silver. Sulphu- 
retted hydrogen produces in it an analogous 
change. This compound, says M. Gay 
Lussac, is evidently the triple hydrocyanate 
of potash and silver ; and its formation 
ought to be analogous to that of the other 
triple hydrocyanates. " And as we cannot 
doubt," adds he, " that hydrocyanate of 
potash and silver is in reality, from the mode 
of its formation, a compound of cyanide of 
silver and hydrocyanate of potash, I conceive 
that the hydrocyanate of potash and iron is 
likewise a compound of neutral hydrocy- 
anate of potash, and subcyanide of iron, 
which I believe to be combined with hydro- 
cyanic acid in the white precipitate. We 
may obtain it perfectly neutral, and then it 
does not decompose alum; but the hydro- 
cyanate of potash, which is always alkaline, 
produces in it a light and flocculent preci- 
pitate of alumina. To the same excess of 
alkali we must ascribe the ochrey colour of 
the precipitates which hydrocyanate of potash 
forms with the persalts of iron. Thus the 
remarkable fact, which ought to fix the at- 
tention of chemists, and which appears to 
me to overturn the theory of Mr Porrett, is, 
that hydrocyanate of potash cannot become 
neutral except when combined with the cya- 
nides." 

ACID (CYANIC). Cyanate of potash 
may be procured in large quantity by heat- 
ing to dull redness a very finely pulverized 
mixture of about equal parts of ferrocyanate 
of potash (well dried) and peroxide of man- 
ganese. If the heat be too great, we shall 
obtain little salt, because the deutoxide form- 
ed appears to change into protoxide at the 
expense of the cyanate. The mass is to be 
boiled with alcohol of moderate strength, 
(0.840 sp. gr.), and on cooling, the salt sepa- 
rates in small plates, resembling chlorate of 
potash. It is insoluble in pure alcohol. 

Cyanate of potash acted on by muriatic 
acid gas is converted into chloride of potas- 
sium, and much sal ammoniac is developed. 
Cyanate of potash, by simple boiling in wa- 
ter, becomes carbonate of potash. By both 
modes of analysis it seems to consist of 
potash 57.95, acid 42.05; whence the prime 
equivalent of the acid would seem to be 
4.45. 100 of cyanate of silver contain 
77.353 of oxide ; a statement agreeing nearly 
with the above equivalent. 

The cyanates acted on by aqueous acids, 
give out their carbon of composition in the 
form of carbonic acid. In this way, the acid 



ACID 



CHLOROCYAN1C. 



constituent of cyanate of silver was analyzed, 
and found to contain, carbon 35.334, azote 
41.317, and oxygen 23.34-9; or cyanogen 
76.651, oxygen 23.349. In fact, 2 atoms of 
carbon = 1.5, -{- 1, azote = 1.75, -f- 1, oxy- 
gen = 1, give a sum = 4.25 ; which, con- 
verted into per cent proportions are, carbon 
35.3, azote 41.7, oxygen 23.53 = 100. 
Hence this acid has the same composition as 
the fulminic acid, though its properties are 
very different. F. Wohler, Ann. de Chim. 
et de Phys. xxvii. 196. 

M. Liebeg states, that cyanic acid may be 
obtained in a separate state, by passing a 
current of sulphuretted hydrogen gas through 
water in which cyanate of silver is diffused. 
The acid reddens litmus strongly ; is sour 
to the taste ; it possesses the smell which is 
always perceived when any of its salts are 
decomposed by an acid ; it neutralizes bases 
perfectly, but when in contact with water it 
suffers decomposition in a few hours, and is 
converted into carbonic acid gas and ammo- 
nia. The sulphuretted hydrogen must not be 
passed so long as to decompose all the cyanate 
of silver; for then the cyanic acid is con- 
verted into other products by the excess of 
the sulphuretted hydrogen. See ACID ( FUL- 
MINIC). 

ACID(CHLOROCYANIC). M. Ber- 
thollet discovered, that when hydrocyanic 
acid is mixed with chlorine, it acquires new 
properties. Its odour is much increased. 
It no longer forms prussian blue with solu- 
tions of iron, but a green precipitate, which 
becomes blue by the addition of sulphurous 
acid. Hydrocyanic acid thus altered had 
acquired the name of oxyprussic, because it 
was supposed to have acquired oxygen. M. 
Gay Lussac subjected it to a minute exami- 
nation, and found that it was a compound 
of equal volumes of chlorine and cyanogen, 
whence he proposed to distinguish it by the 
name of chlorocyanic acid. To prepare this 
compound, he passed a current of chlorine 
into solution of hydrocyanic acid, till it de^ 
stroyed the colour of sulphate of indigo ; and 
by agitating the liquid with mercury, he 
deprived it of the excess of chlorine. By 
distillation, afterwards, in a moderate heat, 
an elastic fluid is disengaged, which possesses 
the properties formerly assigned to oxyprussic 
acid. This, however, is not pure chlorocy- 
anic acid, but a mixture of it with carbonic 
acid, in proportions which vary so much as 
to make it difficult to determine them. 

When hydrocyanic acid is supersaturated 
with chlorine, and the excess of this last is 
removed by mercury, the liquid contains 
chlorocyanic and muriatic acids. Having 
put mercury into a glass jar until it was 
3-4ths full, he filled it completely with that 
acid liquid, and inverted the jar in a vessel 
of mercury. On exhausting the receiver of 
an air-pump containing this vessel, the mer- 



cury sunk in the jar, in consequence of the 
elastic fluid disengaged. By degrees the 
liquid itself was entirely expelled, and swam 
on the mercury on the outside. On admit- 
ting the air, the liquid could not enter the 
tube, but only the mercury, and the whole 
elastic fluid condensed, except a small bubble. 
Hence it was concluded that chlorocyanic 
acid was not a permanent gas, and that, in 
order to remain gaseous under the pressure 
of the air, it must be mixed with another 
gaseous substance. 

The mixture of chlorocyanic and carbonic 
acids has the following properties. It is 
colourless. Its smell is very strong. A very 
small quantity of it irritates the pituitory 
membrane, and occasions tears. It reddens 
litmus, is not inflammable, and does not de- 
tonate when mixed with twice its bulk of 
oxygen or hydrogen. Its density, deter- 
mined by calculation, is 2. 1 1 1 . Its aqueous 
solution does not precipitate nitrate of silver, 
nor baryta water. The alkalis absorb it 
rapidly ; but an excess of them is necessary 
to destroy its odour. If we then add an 
acid, a strong effervescence of carbonic acid 
is produced, and the odour of chlorocyanic 
acid is no longer perceived. If we add an 
excess of lime to the acid solution, ammonia 
is disengaged in abundance. To obtain the 
green precipitate from solution of iron, we 
must begin by mixing chlorocyanic acid with 
that solution. We then add a little potash, 
and at last a little acid. If we add the 
alkali before the iron, we obtain no green 
precipitate. 

M. Gay Lussac deduces for the composi- 
tion of chlorocyanic acid 1 volume of carbon 
-|- ^ a volume of azote -f- ^ a volume of 
chlorine ; and when decomposed by the suc- 
cessive action of an alkali and an acid, it 
produces one volume of muriatic acid gas -|- 
1 volume of carbonic acid -|- 1 volume of 
ammonia. The above three elements sepa- 
rately constituting two volumes, are con- 
densed, by forming chlorocyanic acid into 
one volume. And since one volume of 
chlorine, and one volume of cyanogen, pro- 
duce two volumes of chlorocyanic acid, the 
density of this last ought to be the half of 
the sum of the densities of its two consti- 
tuents. Density of chlorine is 2.421, den- 
sity of cyanogen 1.801, half sum = 2.111, 
as stated above : Or the proportions by 
weight will be 3.25 = a prime equivalent 
of cyanogen -{- 4.5 = a prime of chlorine, 
giving the equivalent of chlorocyanic acid = 
7.75. 

Chlorocyanic acid exhibits with potassium 
almost the same phenomena as cyanogen. 
The inflammation is equally slow, and the 
gas diminishes as much in volume. 

Serullas prepares chlorocyanic acid as fol- 
lows : He fills a large matrass with chlo- 
rine, and then introduces into it, for every 



ACID 



FERROCYANIC. 



ten cubic inches of gas, twenty-four grains 
of cyanide of mercury, pulverized and moist. 
The matrass is now corked, and set aside for 
ten or twelve hours in a dark place. At the 
end of this time the chlorine has combined 
with the mercury and the cyanogen. The 
chlorocyanic acid (chloride cyaneux of Ber- 
zelius) is gaseous, and occupies the place 
of the chlorine. The matrass must be next 
artificially cooled to F., at which tem- 
perature the gaseous acid is condensed into 
a solid. The matrass must now be filled 
with mercury cooled below zero of Fahren- 
heit; a cork is to be fitted to its mouth, 
through which a tube passes, ending in ano- 
ther filled with fragments of dried muri- 
ate of lime. Through this the gas must 
pass in leaving the matrass. The mercury 
must now be slightly heated; the chloro- 
cyanic acid resumes the gaseous state, and 
may then be collected over the pneumatic 
shelf. The use of the cold mercury is to 
expel the atmospheric air, and the residuum 
of chlorine. At F. it crystallizes in long 
prismatic needles, which have no smell, or 
at least a very slight one. At 5 F. it 
melts into a liquid ; and at 14 F. it boils. 
At 68 F. it requires a pressure of four at- 
mospheres for its condensation into a liquid, 
which is colourless and transparent. 

Water absorbs 25 times its bulk of chlo- 
rocyanic acid gas, and gives it out in ebulli- 
tion, without any change in its nature. The 
solution does not redden litmus, nor does it 
precipitate the salts of silver. It may be 
preserved a long time without decomposition. 
Alcohol absorbs 100, and ether 50 times its 
volume of this acid gas. The salifiable bases 
decompose it, and destroy the cyanogen. 

This gas gives a green colour to the salts 
of iron. To produce this phenomenon, 
chlorocyanic acid must be introduced into a 
solution of a salt of iron, and then a little 
free alkali must be added. Chlorocyanic 
acid is composed of 57.29 chlorine, and 
42.71 cyanogen, or a volume of each, as 
originally demonstrated by Gay Lussac. 

When, in preparing the chlorocyanic acid, 
the matrass is exposed to the sunbeam, a 
combination is produced somewhat different 
from the preceding. It is not gaseous, but 
oleaginous, yellow, and dense. It is inso- 
luble in water, but soluble in alcohol. Its 
nature is not well understood ; but it proba- 
bly consists of a combination of cyanogen, 
with more chlorine than exists in the chloro- 
cyanic acid. 

ACID (PERCHLOROCYANIC), or 
Perchloride of Cyanogen, has been lately dis- 
covered by Serullas. To obtain it, he takes 
a bottle of the capacity of fully two pints 
(imperial) ; introduces into it very dry chlo- 
rine gas, till the atmospheric air be expelled ; 
then he puts in fifteen grains of anhydrous 
hydrocyanic acid. It is now corked and 



exposed for some days to the sunbeams. 
The chlorine gas is converted into muriatic 
acid, and the perchloride of cyanogen crys- 
tallizes on the inner surface of the glass. 
Too much hydrocyanic acid produces a mass 
of a deep red colour, similar to tallow in 
consistence, which a larger quantity of chlo- 
rine converts into the perchloride. The 
muriatic gas may be expelled from the bot- 
tle, by blowing in dry air ; a little water is 
then dropped in, and some fragments of 
glass, by means of which the perchloride is 
detached. When the substance is taken 
out, it must be dried and distilled. It forms 
now white crystalline needles. Its odour 
is acrid, resembling somewhat the smell of 
mice ; and its taste is slight. Its density is 
1.32. It fuses at 284 F., and sublimes at 
374 F. Hardly soluble in cold water, it 
is decomposed in boiling water. Ether and 
alcohol dissolve it, and water precipitates it 
from these solutions. It consists of 72.85 
parts of chlorine, and 27.15 cyanogen, or 
2 volumes of the first, and 1 of the second. 

ACID (FERROCYANIC). Into a so- 
lution of the amber-coloured crystals, usually 
called prussiate of potash, pour hydrosulphu- 
ret of baryta, as long as any precipitate falls. 
Throw the whole on a filter, and wash the 
precipitate with cold water. Dry it ; and 
having dissolved 100 parts in cold water, add 
gradually 30 of concentrated sulphuric acid ; 
agitate the mixture, and set it aside to repose. 
The supernatant liquid is the ferroprussic i 
acid of M. Porrett. 

It has a pale lemon-yellow colour, but no 
smell. Heat and light decompose it. Hydro- 
cyanic acid is then formed, and white ferro- 
cyanate of iron, which soon becomes blue. 
Its affinity for the bases enables it to displace 
acetic acid, without heat, from the acetates, 
and to form ferrocyanates. 

When a saline solution contains a base with 
which the ferrocyanic acid forms an insolu- 
ble compound, then, agreeably to Berthollet's 
principle, it is capable of supplanting its acid. 
When ferrocyanate of soda is exposed to vol- 
taic electricity, the acid is evolved at the posi- 
tive pole, with its constituent iron. M. Por- 
rett considers this acid " as a compound of 
4 atoms carbon = 30.00 
I atom azote = 17.50 
1 atom iron = 17.50 

1 atom hydrogen = 1.25 

66.25" 

This sum represents the weight of its prime 
equivalent. Ferrocyanate of potash, and of 
baryta, will each therefore, according to him, 
consist of an atom of acid -f- an atom of 
base -f- two atoms of water. 

Berzelius has shewn, that when sulphuret- 
ted hydrogen gas is transmitted over efflo- 
resced ferruginous prussiate of potash, heated 
in a glass tube by a spirit lamp, no hydro- 
D 



ACID 



50 



FERROCYANIC. 



cyanic acid or water is produced ; and that 
therefore the iron present in the salt is in the 
metallic state. On igniting dry ferrocyanate 
of potash along with peroxide of copper in a 
glass tube, the same chemist found that the 
gaseous products consisted of carbonic acid 
and azote, in the proportion of three volujnes 
of the former to two volumes of the latter. 
The same result was obtained from ferro- 
cyanate of baryta. But as the potash and 
baryta of the above salts retain a portion of 
the carbonic acid, Berzelius next analyzed in 
the same way ferrocyanate of lead : he found 
that the gas collected towards the end of the 
operation, which was quite free from atmos- 
pheric air, was a mixture of two parts of car- 
bonic acid, and one part of azote by volume. 
Hence the carbon and azote in these salts 
exist in the same proportions as in cyanogen : 
no water was produced. He finally con- 
cludes, that the dry ferrocyanates are com- 
posed of one atom of cyanide of iron and 
two atoms of cyanide of the other metal, 
potassium, barium, or lead ; according as it 
is a ferrocyanate of potash, baryta, or lead, 
that is in question. Berzelius considers the 
ferrocyanic or ferruretted chyazic acid of M. 
Porrett as a super-hydrocyanate of iron in an 
impure state. To obtain it pure, he adopted 
the following method : he decomposed well 
washed ferrocyanate of lead, under water, by 
a current of sulphuretted hydrogen gas, re- 
moving the excess of sulphuretted hydrogen 
with a small quantity of ferrocyanate of lead. 
The filtered fluid remained limpid and co- 
lourless in vacua, leaving eventually a milk- 
white substance, which had no appearance of 
crystallization. This white matter has the 
following properties: It dissolves in water, 
to which it imparts an acid and agreeable 
flavour, but which is rather astringent. In 
contact with the air it deposits prussian blue, 
and assumes a greenish colour. It is in- 
odorous, unless it has begun to decompose. 
When boiled, the liquid gives out hydro- 
cyanic acid, and deposits a powder which be- 
comes blue in contact with the air. It is 
necessary to boil it for some time to decom- 
pose it entirely. If cold water be saturated 
with dry super-hydrocyanate, and the solu- 
tion be suffered to remain, it gives small 
transparent colourless crystals, which appear 
to contain water of crystallization. The 
crystals are apparently quadrilateral prisms 
in groups composed of concentric rays. Ber- 
zelius supposes these to be hydrocyanate, in 
which water replaces the second base that 
existed with the protoxide of iron. The 
white substance obtained by evaporation in 
vacuo does not appear to contain any water, 
or rather appears to be the super-hydro- 
cyanate of protoxide of iron, without water 
of crystallization ; for if it be distilled in a 
small and proper apparatus, it gives at first 
hydrocyanic acid ; afterwards carbonate of 



ammonia and hydrocyanate of ammonia. The 
production of ammonia in this experiment 
proves, that what remains after the hydro- 
cyanic acid which is first evolved, is a hydro- 
cyanate, and not a cyanide, because in the 
latter case it could only have given hydro- 
cyanic acid and azotic gas. This substance 
may be kept without alteration in well-closed 
vessels ; but in the air it gradually decom- 
poses, becomes at first greenish, afterwards 
blue, and finishes by being entirely converted 
into prussian blue. 

On the relations of hydrocyanic acid and 
iron, the following observations by M. Vau- 
quelin are curious. Hydrocyanic acid diluted 
with water, when placed in contact with iron 
in a glass vessel standing over mercury, quick- 
ly produces prussian blue, while, at the same 
time, hydrogen gas is given out. The greatest 
part of the prussian blue formed in that 
operation, remains in solution in the liquid : 
it appears only when the liquid comes in con- 
tact with the air. This shows us that prus- 
sian blue, at a minimum of oxidizement, is 
soluble in hydrocyanic acid. Dry hydro- 
cyanic acid placed in contact with iron fil- 
ings, undergoes no change in its colour nor 
smell ; but the iron, which becomes agglu- 
tinated together at the bottom of the vessel, 
assumes a brown colour. After some days, 
the hydrocyanic acid being separated from 
the iron, and put in a small capsule under a 
glass jar, evaporated without leaving any re- 
sidue. Therefore it had dissolved no iron. 
Hydrocyanic acid dissolved in water, placed 
in contact with hydrate of iron, obtained by 
means of potash, and washed with boiling 
water, furnished prussian blue immediately, 
without the addition of any acid. Scheele 
has made mention of this fact. When hydro- 
cyanic acid is in excess on the oxide of iron, 
the liquor which floats over the prussian blue 
assumes, after some time, a beautiful purple 
colour. The liquor, when evaporated, leaves 
upon the edge of the dish circles of blue, and 
others of a purple colour, and likewise crys- 
tals of this last colour. When water is poured 
upon these substances, the purple-coloured 
body alone dissolves, and gives the liquid a 
fine purple colour. The substance which 
remains undissolved is prussian blue, which 
has been held in solution in the hydrocyanic 
acid. Some drops of chlorine let fall into 
this liquid change it to blue, and a greater 
quantity destroys its colour entirely. It is 
remarkable, that potash poured into the liquid 
thus deprived of its colour, occasions no pre- 
cipitate whatever. 

Chemists will not fail to remark from these 
experiments, that hydrocyanic acid does not 
form prussian blue directly with iron; but 
that, on the addition of water, (circumstances 
remaining the same), prussian blue is pro- 
duced. They will remark, likewise, that 
cyanogen united to water dissolves iron. 



ACID 



FERROCYANIC. 



This is confirmed by the inky taste which it 
acquires, by the disappearance of its colour, 
and by the residue which it leaves when eva- 
porated: yet prussian blue is not formed. 
These experiments seem to show that prussian 
blue is a hydrocyanate, and not a cyanide. 

The ammonia, and hydrocyanic acid, dis- 
engaged during the whole duration of the 
combustion of prussian blue, give a new sup- 
port to the opinion that this substance is a 
hydrocyanate of iron ; and likewise the results 
which are furnished by the decomposition of 
prussian blue by heat in a retort, show clear- 
ly that it contains both oxygen and hydrogen, 
which are most abundant towards the end, 
long after any particles of adhering water 
must have been dissipated. , 

Such compounds we shall call ferrocya- 
nates. M. Vauquelin and M. Thenard styled 
them ferruginous prussiates. 

Ferrocyanate of potash. Into an egg- 
shaped iron pot, brought to moderate igni- 
tion, project a mixture of good pearl-ash and 
dry animal matters, of which hoofs and horns 
are best, in the proportion of two parts of the 
former to five of the latter. Stir them well 
with a flat iron paddle. The mixture, as it 
calcines, will gradually assume a pasty form, 
during which transition it must be tossed 
about with much manual labour and dexte- 
rity. When the conversion into a chemical 
compound is seen to be completed by the 
cessation of the fetid animal vapours, remove 
the pasty mass with an iron ladle. 

If this be thrown, while hot, into water, 
some of the prussic acid will be converted 
into ammonia, and of course the usual pro- 
duct diminished. Allow it to cool, dissolve 
it in water, clarify the solution by filtration 
or subsidence, evaporate, and, on cooling, 
yellow crystals of the ferroprussiate of potash 
will form. Separate these, redissolve them 
in hot water, and, by allowing the solution 
to cool very slowly, larger and very regular 
crystals may be had. This salt is now manu- 
factured in several parts of Great Britain on 
the large scale ; and therefore the experimen- 
tal chemist need not incur the trouble and 
nuisance of its preparation. Nothing can 
exceed in beauty, purity, and perfection, the 
crystals of it prepared at Campsie, by Mr 
Macintosh. 

An extemporaneous ferroprussiate of pot- 
ash may at any time be made, by acting on 
prussian blue with pure carbonate of potash, 
prepared from the ignited bicarbonate or bi- 
tartrate. The blue should be previously di- 
gested at a moderate heat, for an hour or two, 
in its own weight of sulphuric acid, diluted 
with five times its weight of water ; then fil- 
tered, and thoroughly edulcorated by hot 
water from the sulphuric acid. Of this pu- 
rified prussian blue add successive portions 
to the alkaline solution, as long as its colour 
is destroyed, or while it continues to change 



from blue to brown. Filter the liquid, sa- 
turate the slight alkaline excess with acetic 
acid, concentrate by evaporation, and allow 
it slowly to cool. Quadrangular bevelled 
crystals of the ferroprussiate of potash will 
form. 

This salt is transparent, and of a beautiful 
lemon or topaz-yellow. Its specific gravity 
is 1.830. It has a saline, cooling, but not 
unpleasant taste. In large crystals it pos- 
sesses a certain kind of toughness, and, in 
thin scales, of elasticity. The inclination of 
the bevelled side to the plane of the crystal 
is about 135. It loses about 13 per cent 
of water when moderately heated ; and then 
appears of a white colour, as happens to the 
green copperas ; but it does not melt like 
this salt. The crystals retain their figure 
till the heat verges on ignition. At a red 
heat it blackens, but, from the mode of its 
formation, we see that even that temperature 
is compatible with the existence of the acid, 
provided it be not too long continued. Wa- 
ter at 60 dissolves nearly one-third of its 
weight of the crystals ; and at the boiling 
point almost its own weight. It is not solu- 
ble in alcohol ; and hence chemical compi- 
lers, with needless scrupulosity, have assigned 
to that liquid the hereditary sinecure of 
screening the salt from the imaginary dan- 
ger of atmospherical action. It is not altered 
by the air. Exposed in a retort to a strong 
red heat, it yields prussic acid, ammonia, 
carbonic acid, and a coaly residue, consist- 
ing of charcoal, metallic iron, and potash. 
When dilute sulphuric or muriatic acid is 
boiled on it, prussic acid is evolved, and a 
very abundant white precipitate of proto- 
prussiate of iron and potash falls, which af- 
terwards, treated with liquid chlorine, yields 
a prussian blue, equivalent to fully one-third 
of the salt employed. Neither sulphuretted 
hydrogen, the hydrosulphurets, nor infusion 
of galls, produce any change on this salt. 
Red oxide of mercury acts powerfully on its 
solution at a moderate heat. Prussiate of 
mercury is formed, which remains in solu- 
tion; while peroxide of iron and metallic 
mercury precipitate. Thus we see that a 
portion of the mercurial oxide is reduced, 
to carry the iron to the maximum of oxidize- 
ment. 

The solution of ferroprussiate of potash is 
not affected by alkalis ; but it is decomposed 
by almost all the salts of the permanent 
metals. The following table presents a view 
of the colours of the metallic precipitates thus 
obtained. 

Solutions of Give a 

Manganese, White precipitate. 

Protoxide of iron, Copious white. 

Deutoxide of iron, Copious clear blue. 

Tritoxide of iron, Copious dark blue. 

Tin, White. 



ACID 



52 



FERROCYANIC. 



Solutions of Give a 

Zinc, White. 

Antimony, White. 

Uranium, Blood-coloured. 

Cerium, White. 

Cobalt, Grass-green. 

Titanium, Green. 

Bismuth, White. 

Protoxide of copper, White. 
Deutoxide of copper, Crimson-brown. 
Nickel, Apple-green. 

Lead, White. 

Deutoxide of mercury, White. 
Silver, White, passing to blue 

in the air. 

Palladium, Olive. 

Rhodium, Platinum, 

and Gold, None. 

If some of these precipitates, for example 
those of manganese or copper, be digested in 
a solution of potash, we obtain a ferrocya- 
nate of potash and iron, exactly similar to 
what is formed by the action of the alkaline 
solution on prussian blue. These precipi- 
tates, therefore, contain a quantity of iron. 

The researches of Berzelius have shewn 
that dry ferrocyanate of potash is truly a 
compound of one atom of cyanide of iron, 
with two atoms of cyanide of potassium. Its 
composition may therefore be stated as fol- 
lows : 

With water of cryst. 

(Iron 3.50 15.05 13.15 
1 lcyanogen=3.25) 41943662 

Potassium== 10.00 43.00 37.56 
Water 12.67 

foooo 



2 atoms 



2325 

In its crystallized state it contains three 
atoms of water, which makes its prime equi- 
valent in that case 23.25 + 3.375 = 26.625. 
To convert this weight into ferrocyanate of 
lead, two atoms of nitrate of lead will be re- 
quired = 41.5 ; so that one atom of nitrate of 

lead = 20.75, will be equivalent to ' = 

13.3125 of crystals of ferrocyanate of potash. 
These 13.3125 parts of salt, by the action of 
nitrate of lead, afford 12.75 parts of nitre, 
which contain six of potash. 

Red ferrocyanate of potash. M. Girardin 
obtained this compound by passing chlorine 
gas into a moderately strong solution of the 
common ferrocyanate of potash, which is to 
be continued until the solution ceases to pro- 
duce any effect when added to a solution of 
peroxide of iron. The liquor is then to be 
concentrated to two-thirds of its volume, and 
set aside in a moderately warm stove to crys- 
tallize: after some time, yellow, brilliant, 
and slender crystals are obtained in form of 
roses ; by a second crystallization, very long 
needle-form crystals are procured in tufts, 



These crystals are ruby-coloured, transpa- 
rent, and very brilliant; their form appears 
to be elongated octahedrons. 

The principal character of this salt is that 
of indicating the proto-salts of iron, precipi- 
tating them blue or green, according to the 
proportion in solution ; and, on the contrary, 
not precipitating the per-salts of iron. This 
reagent, according to M. Girardin, is much 
more sensible than the common ferrocyanate 
of potash, for it is capable of detecting one 
90,000dth of protoxide of iron, while the lat- 
ter salt does not detect less than one 1800dth 
of the protoxide. 

The red ferrocyanate is soluble in twice its 
weight of cold water, and less than its own 
weight of boiling water. It is insoluble in 
alcohol, does not act on litmus, but renders 
syrup of violets green. A very small quan- 
tity renders a considerable portion of water 
green. In the formation of this salt, half of 
the acid of the ferrocyanate is destroyed by 
the chlorine, and the alkali of this half gets 
combined with muriatic acid: the ferro- 
cyanates of soda, ammonia, baryta, and lime, 
are all converted into red ferrocyanates by 
chlorine. 

The red ferrocyanate of potash precipitates 
tin white ; silver and zinc of an orange co- 
lour ; nickel, bismuth, and titanium, brown ; 
copper, dirty brown ; cobalt and uranium, dif- 
ferent shades of reddish-brown ; both oxides 
of mercury, brown : lead is not precipitated, 
but after some time reddish-brown crystals 
are deposited, which, when decomposed by 
sulphuric acid, separate per-ferrocyanic acid, 
which crystallizes in needles, reddens litmus 
paper, and has a taste at first acid, then styp- 
tic. When slightly heated it resolves itself into 
hydrocyanic acid and prussian blue, Hens- 
man's Repertoire de Chimie, Aug. 1828. 

Ferrocyanate of soda may be prepared 
from prussian blue and pure soda, by a simi- 
lar process to that prescribed for the preced- 
ing salt. It crystallizes in four-sided prisms, 
terminated by dihedral summits. They are 
yellow, transparent, have a bitter taste, and 
effloresce, losing in a warm atmosphere 37| 
per cent. At 55 they are soluble in 4^ parts 
of water, and in a much less quantity of boil- 
ing water. As the solution cools, the crystals 
separate. Their specific gravity is 1.458. 
They are said by Dr John to be soluble in 
alcohol. 

Its constituents are as follows : 

(Iron = 3.50 11.48 

1 atom -{ /-, o OK 

i I 'trannrrtm n .TH I \ 

2 atoms 




10 atoms Water 



11.25 



19.67 

36.88 



30.50 100.00 

Ferrocyanate of lime may be easily formed 
from prussian blue and lime water. Its solu- 
tion yiejds crystalline grains by evaporation. 



ACID 



53 



FERROCYANIC. 



It consists of 

Iron, 3.50 11.86 

Cyanogen, 9.75 33.05 

Calcium, 5.00 16.96 

Water, 11.25 38.13 

29.50 100.00 

The preceding results, as also those of 
Berzelius on the ferrocyanide of lead, being 
apparently discordant with those which I have 
stated in my paper on the ultimate analysis 
of organic compounds (Phil. Trans. 1822), 
a few words of explanation seem requi- 
site. I found that an atom of nitrate of 
lead = 20.75, was, by the method of double 
decomposition, equivalent to 13. 125 of crys- 
tallized ferrocyanide of potassium ; whence 
I inferred that this was its atomic weight. 
According to Berzelius, 20. 75 parts of nitrate 
of lead are equivalent to 13.3175 of the 
crystallized ferrocyanide of potassium. This 
difference, though small, would have excited 
my surprise, considering the pains that I took, 
had not Berzelius shewn that ferrocyanide of 
lead is apt to carry down, in its precipitation, 
a portion of nitrate of that metal, to which 
circumstance I ascribed the above discrepancy. 
By my experiments, 13.3175 grains of the 
crystallized ferroprussiate of potash afford 
5.9 of potash, a result not wide of the truth. 
From 21 grains of ferrocyanide of lead I 
obtained 2.625 grains of peroxide of iron, 
= 1.8375 of metallic iron, while, by Berze- 
lius, the quantity of iron present is 1.87, a 
difference only in the second place of deci- 
mals. But with regard to my products in 
the igneous decomposition by peroxide of cop- 
per, I am satisfied that a portion of the azote 
combined with the oxygen of the peroxide 
into a liquid compound, whence the gaseous 
analysis was vitiated. 20.75 parts of nitrate 
of lead, containing 14 of oxide, or 13 of 
metal, should yield by Berzelius 19.625 of 
ferrocyanide of lead ; but I obtained 21, no 
doubt in consequence of some nitrate falling 
down along with it. 

From 13.125 grains of ferrocyanate of 
potash I obtained 1.69 of water, which is 
12.87 per cent. Berzelius obtained from 
12.4 to 12.9, his calculated atomic propor- 
tion being 12.67. Had it occurred to me 
to double the above product 1.69, then the 
number 3.38, being as nearly as possible 3 
atoms of water =3.375, would have un- 
ravelled all the intricacy, and have satisfied 
me that the complex constitution assigned 
by Berzelius was the true one, since it gave 
the fewest integer atoms of the constituents. 
Ferrocyanate of baryta may be formed in 
the same way as the preceding species. Its 
crystals are rhomboidal prisms, of a yellow 
colour, and soluble in 2000 parts of cold 
water and 100 of boiling water. 

According to Berzelius, ferrocyanate of 
baryta consists of 



Iron, 3.500 

Cyanogen, 9.750 
Barium, 17.500 
Water, 5.625 



9.62 
26.80 
48.11 
15.47 



36.375 100.00 

Ferrocyanate of strontia and magnesia 
have also been made. 

Ferrocyanide of lead is formed by pouring 
neutral nitrate of lead into a solution of fer- 
rocyanate of potash, taking care that the 
latter be in excess, in order to prevent the 
precipitation of nitrate of lead, which mixes 
with all the insoluble salts with base of oxide 
of lead, if there be an excess of nitrate of 
lead in the liquid from which they are depo- 
sited. The liquid remains perfectly neutral. 
The precipitate is white with a cast of yel- 
low. . Its compsoition is as follows: 
Iron, 3.50 . . 8.92 

Cyanogen, 9.75 . . 24.84 
Lead, 26.00 . . 66.24 

39.25 100.00 

In its state of ordinary dryness it contains 
three atoms of water. 

Ferrocyanate of iron. We have already 
described the method of making the ferro- 
cyanate of potash, which is the first step in 
the manufacture of this beautiful pigment. 
This is usually made by mixing together one 
part of the ferrocyanate of potash, one part 
of copperas, and four parts of alum, each pre- 
viously dissolved in water. Prussian blue, 
mixed with more or less alumina, precipitates. 
It is afterwards dried on chalk stones in a stove. 

Pure prussian blue is best prepared by 
dropping a solution of ferrocyanate of iron 
into a solution of red muriate of iron, to 
which a slight excess of acid is previously 
added. The precipitate must be thoroughly 
washed and dried. It retains hygrometric 
moisture so strongly, that sulphuric acid in 
vacuo does not detach it. 

Berzelius found that a portion of very dry 
prussian blue, when lighted at the edge, con- 
tinued to burn by itself like amadou, giving 
a vapour which condensed on a funnel in- 
verted over it : it was carbonate of ammonia. 
One hundred parts of such prussian blue left 
a residuum of 60.14 parts of red oxide of 
iron, containing no potash. 

When a solution of protoxide of iron is pre- ' 
cipitated by cyanide of iron and potassium, a 
white insoluble compound is formed, which 
contains potash, and which, by absorbing 
oxygen, becomes blue. But it is well known, 
that a salt with base of protoxide, which 
absorbs oxygen without there being an in- 
crease of acid, combines with an excess of 
base. Prussian blue, therefore, which is pre- 
pared by oxidation of the white precipitate, 
cannot be a neutral compound. Prussian 
blue, thus prepared, has properties which it 
does not possess when differently prepared, 



ACID 



SULPHOCYANIC. 



It is soluble in pure water, but not in water 
whicli contains a certain quantity of any 
neutral salt. Thus there are evidently two 
blue combinations: The one composed of 
3 atoms of hydrocyanate of protoxide, and 4 
atoms of hydrocyanate of deutoxide, in which 
the acid and oxygen of the second part is 
, double that of the first ; and another, appa- 
rently composed of 1 atom of hydrocyanate 
of protoxide, and 2 atoms of hydrocyanate 
of deutoxide. 

Pure prussian blue is a mass of an ex- 
tremely deep blue colour, insipid, inodorous, 
and considerably denser than water. Neither 
water nor alcohol has any action on it. Boil- 
ing solutions of potash, soda, lime, baryta, 
and strontia, decompose it ; forming on one 
hand soluble ferrocyanates with these bases, 
and on the other a residue of brown peroxide 
of iron, and a yellowish-brown sub-ferrocya- 
nate of iron. This last, by means of sul- 
phuric, nitric, or muriatic acids, is brought 
back to the state of a ferrocyanate, by ab- 
stracting the excess of iron oxide. Aqueous 
chlorine changes the blue to a green in a few 
minutes, if the blue be recently precipitated. 
Aqueous sulphuretted hydrogen reduces the 
blue ferrocyanate to the white proto- ferro- 
cyanate. 

Its igneous decomposition in a retort was 
executed by M. Vauquelin with minute at- 
tention. He regards it as a hydrocyanate, 
or mere cyanide of iron ; but the changes he 
describes are very complex. The general 
results of M. Vauquelin's analysis were hy- 
drocyanic acid, hydrocyanate of ammonia, an 
oil soluble in potash, crystalline needles, 
which contained no hydrocyanic acid, but 
were merely carbonate of ammonia; and 
finally, a ferreous residue slightly attracted 
by the magnet, and containing a little unde- 
composed prussian blue. 

Proust, in the Annales de Chimie, vol. Ix. 
states, that 100 parts of prussian blue, with- 
out alum, yield 0.55 of red oxide of iron by 
combustion; and by nitric acid, 0.54. 100 
of cyanate of potash and iron, he further 
says, afford, after digestion with sulphuric 
or nitric acid, 35 parts of prussian blue. 

Ferrocyanate of ammonia is best prepared 
by acting on ferrocyanate of lead with caus- 
tic ammonia. The solution being evaporated 
in vacuo, a pulverulent salt is obtained. It 
is a hydrocyanate of protoxide of iron, com- 
bined with hydrocyanate of ammonia. 

ACID (SULPHOCYANIC). The sul- 
phuretted chyazic acid of M. Porrett. 

Dissolve in water one part of sulphuret of 
potash, and boil it for a considerable time 
with three or four parts of powdered prussian 
blue added at intervals. Sulphuret of iron 
is formed, and a colourless liquid, containing 
the new acid combined with potash, mixed 
with hyposulphate and sulphate of potash. 
Render this liquid sensibly sour, by the ad- 



dition of sulphuric acid. Continue the boiling 
for a little, and when it cools add a little per- 
oxide of manganese in fine powder, which 
will give the liquid a fine crimson colour. 
To the filtered liquid add a solution contain- 
ing persulphate of copper and protosulphate 
of iron, in the proportion of two of the former 
salt to three of the latter, until the crimson 
colour disappears. Sulphurocyanide of cop- 
per falls. Boil this with a solution of potash, 
which will separate the copper. Distil the 
liquid mixed with sulphuric acid in a glass 
retort, and the peculiar acid will come over. 
By saturation with carbonate of baryta, and 
then throwing down this by the equivalent 
quantity of sulphuric acid, the sulphuro- 
prussic acid is obtained pure. 

It is a transparent and colourless liquid, 
possessing a strong odour, somewhat resem- 
bling acetic acid. Its specific gravity is only 
1.022. It dissolves a little sulphur at a boil- 
ing heat. It then blackens nitrate of silver ; 
but the pure acid throws down the silver 
white. By repeated distillations sulphur is 
separated and the acid is decomposed. M. 
Porrett, in the Annals of Phil, for May 1819, 
states the composition of this acid, as it exists 
in the sulphuretted chyazate of copper, to he, 
2 atoms sulphur = 4.000 
2 carbon =1.508 

1 azote =1.754 

1 hydrogen = 0. 132 

7^94 

This is evidently an atom of the hydrocy- 
anic acid of M. Gay Lussac, combined with 
2 of sulphur. If to the above we add 9 for 
an atom of protoxide of copper, we have 
16.394 for the prime equivalent of the me- 
tallic salt. When cyanogen and sulphuret- 
ted hydrogen were mixed together by M. Gay 
Lussac in his researches on the prussic prin- 
ciple, he found them to condense into yellow 
acicular crystals. M. Porrett has since re- 
marked, that these crystals are not formed 
when the two gases are quite dry, but that 
they are quickly produced if a drop of water 
is passed up into the mixture. He does not 
think their solution in water corresponds to 
liquid sulphuretted chyazic acid : it does not 
change the colour of litmus ; it has no effect, 
on solutions of iron ; it contains neither prus- 
sic nor sulphuretted chyazic acid; yet this 
acid is formed in it when it is mixed first with 
an alkali and then with an acid. The same 
treatment does not form any prussic acid. 

M. Gay Lussac states, that the yellow 
needles obtained from the joint action of 
cyanogen and sulphuretted hydrogen, are 
" composed of 1 volume of cyanogen, and 
1 volumes of sulphuretted hydrogen." 

The sulphocyanate of the red oxide of iron 
is a deliquescent salt, of a beautiful crimson 
colour. It may be obtained in a solid form 
by an atmosphere artificially dried. 



ACID 



HYDROXANTHIC. 



Grotthus and Voge), by fusing sulphur 
with ferrocyanate of potash, dissolving, fil- 
tering, and drying, obtained a substance 
which Berzelius has shewn to be a sulpho- 
eyanide of potassium. Though he was not 
able to separate the sulphocyanogen or sul- 
phuret of cyanogen from the base, so as to 
have it in a separate state, yet he deduced 
its composition, from experiments, as being 
one atom of cyanogen 3.25, -f- two atoms of 
sulphur 4, = 7. 25. 

The sulphocyanide of potassium is com- 
posed of potassium one atom 5, -J- sulpho- 
cyanogen one atom 7.25, = 12.25. 

MM. Tiedmann and Gmelin proved the 
presence of sulphocyanide of potassium in 
the saliva of man ; and of sulphocyanide of 
sodium in that of the sheep. By distilling 
human saliva, I have obtained a product of 
sulphocyanic acid in the receiver. See 
OPIUM, and SALIVA. 

Sulphocyanic acid consists of one atom of 
hydrogen 0.125, -f- one atom of sulpho- 
cyanogen 7.25, = 7.375. On substituting 
selenium for sulphur, a selenio-cyanide of 
potassium was formed, perfectly analogous to 
the sulphocyanide. 

Professor Zeise of Copenhagen describes 
(Ann. de Ch. et Phys. xxvi.) a new acid, and 
a new class of salts, produced by mixing in 
a wide-mouthed flask 16 measures of sulphu- 
ret of carbon with 45 measures of alcohol, 
and 100 measures of alcohol saturated with 
ammoniacal gas, at a temperature of 53 F. 
Two sets of crystals form. The first are 
finished in an hour or two, and have a feathery 
aspect. He considers them to be hydroxan- 
thate of ammonia. The formation of the 
second set of crystals takes 30 or 40 hours. 
These are distinctly grouped in stars, have 
considerable lustre, and a prismatic form. 
They are hydrosulphuretted hydrosulphocy- 
anate of ammonia. The flask or phial should 
be well closed with a ground stopper during 
the formation of these crystals, which are 
usually of a bright yellow colour. The salts 
of peroxide of copper produce, in the solution 
of that salt in water, a yellow flocculent pre- 
cipitate. This seems to be a compound of 
ordinary hydrosulphocyanic acid with bisul- 
phuret of copper. On dissolving one part 
of hydrosulphuretted hydrosulphocyanate of 
ammonia in about 180 of water, adding sul- 
phuric or muriatic acids diluted with 16 parts 
of water, till there be an acid excess, and 
then dropping into this mixture, in succes- 
sive small portions, a solution of red oxide of 
iron in sulphuric or muriatic acid, the liquid 
becomes a little dark and muddy, but it soon 
brightens up, with the formation in great 
abundance of crystalline white scales, which 
rapidly settle to the bottom. These crystals 
are to be taken out, and dried by pressure 
between folds of filtering paper. This mat- 
ter contains no iron ; but is a peculiar com- 



pound of sulphur, carbon, azote, and hydro- 
gen, to which M. Zeise gives the name of 
crystalline hydrosulphuret of cyanogen, com- 
posed probably of 1 atom of azote, 2 of car- 
bon, 4 of sulphur, and 2 of hydrogen. Hy- 
drosulphuretted hydrosulphocyanate of am- 
monia is represented as containing 1 atom 
ammonia 2. 125, 1 hydrosulphocyanic acid 
7.375, and 1 sulphuretted hydrogen 2.125, 
= 11.625. See ACID (HYDROXANTHIC). 

ACID(HYDROSELENIC). The best 
process which we can employ for procuring 
this acid, according to M. Berzelius, con- 
sists in treating the seleniuret of iron with 
the liquid muriatic acid : (Ann. de Chim. 
et de Phys. ix. 243.) The acid gas evolved 
must be collected over mercury. As in this 
case a little of another gas, condensible nei- 
ther by water nor alkaline solutions, appears, 
the best substance for obtaining absolutely 
pure hydroselenic acid would be seleniuret 
of potassium. 

Seleniuretted hydrogen gas is colourless. 
It reddens litmus. Its density has not been 
determined by experiment. Its smell re- 
sembles, at first, that of sulphuretted hydro- 
gen gas ; but the sensation soon changes, 
and another succeeds, which is at once pun- 
gent, astringent, and painful. The eyes 
become almost instantly red and inflamed, 
and the sense of smelling entirely disappears. 
A bubble of the size of a little pea is suffi- 
cient to produce these effects. Of all the 
bodies derived from the inorganic kingdom, 
seleniuretted hydrogen is that which exercises 
the strongest action on the animal economy. 
Water dissolves this gas ; but in what pro- 
portions is not known. This solution dis- 
turbs almost all the metallic solutions, pro- 
ducing black or brown precipitates, which 
assume, on rubbing with polished haematites, 
a metallic lustre. Zinc, manganese, and 
cerium, form exceptions. They yield flesh- 
coloured precipitates, which appear to be 
hydroseleniurets of the oxides, whilst the 
others, for the most part, are merely metallic 
seleniurets. 

ACID (HYDROXANTHIC). If a 
certain quantity of sulphuret of carbon be 
poured into an alcoholic solution of one of 
the alkalis, a neutral liquid is obtained, in 
consequence of the formation of a new acid, 
which neutralizes the alkali. If potash has 
been used, the salt may be obtained either 
by refrigeration, evaporation, or precipitation 
by sulphuric ether. It contains no carbonic 
acid, or sulphuretted hydrogen, but an acid 
which is in the same relation to sulphuret of 
carbon that hydrocyanic acid is to cyanogen. 
Its compounds have been called hydroxan- 
thates. The acid may be obtained by pour- 
ing a mixture of four parts of sulphuric acid 
and three of water on the salt of potash, and 
in a few seconds adding abundance of water. 
The acid collects at the bottom of the water 



ACID 



56 



INDIGOIC. 



as a transparent slightly coloured oil ; it must 
be quickly washed with water until free from 
sulphuric acid. This acid reddens litmus pa- 
per powerfully. Its odour differs from that 
of sulphuret of carbon. Its taste is acid and 
astringent. It burns readily, giving out sul- 
phurous fumes. Dr Zeise of Copenhagen, 
Journal of Science, xv. 304. 

ACID (HYPONITROUS). See ACID 
( NITRIC). 

ACID (HYPOPHOSPHORIC). See 
ACID (PHOSPHORIC). 

ACID(HYPOPHOSPHOROUS). See 
ACID (PHOSPHOROUS). 

ACID (HYPOSULPHURIC). See 
ACID (SULPHURIC). 

ACID (HYPOSULPHUROUS). See 
ACID (SULPHUROUS). 

ACID (IGASURIC). MM. Pelletier 
and Caventou, in their elegant researches on 
ihefaba Sancti Jgnatii, et nux vomica, hav- 
ing observed that these substances contained 
a new vegetable base (strychnine) in combi- 
nation with an acid, sought to separate the 
latter, in order to determine its nature. It 
appeared to them to be new, and they called 
it igasuric acid, from the Malay name by 
which the natives designate in the Indies the 
faba Sancti Ignatii. This bean, according 
to these chemists, is composed of igasurate of 
strychnine, a little wax, a concrete oil, a yel- 
low colouring matter, gum, starch, bassorine, 
and vegetable fibre. 

To extract th6 acid, the rasped bean must 
be heated in ether, in a digester, with a valve 
of safety. Thus the concrete oil, and a little 
igasurate of strychnine, are dissolved out. 
When the powder is no longer acted on by 
the ether, they subject it, at several times, to 
the action of boiling alcohol, which carries off 
the oil which had escaped the ether, as also 
wax, which is deposited on cooling, some 
igasurate of strychnine, and colouring mat- 
ter. All the alcoholic decoctions are united, 
filtered, and evaporated. The brownish-yel- 
low residuum is diffused in water ; magnesia 
is now added, and the whole is boiled toge- 
ther for some minutes. By this means the 
igasurate is decomposed, and from this de- 
composition there results free strychnine, 
and a sub-igasurate of magnesia, very little 
soluble in water. Washing with cold water 
removes almost completely the colouring 
matter, and boiling alcohol then separates the 
strychnine, which falls down as the liquid 
cools. Finally, to procure igasuric acid 
from the sub-igasurate of magnesia, which 
remains united to a small quantity of colour- 
ing matter, we must dissolve the magnesian 
salt in a great body of boiling distilled 
water ; concentrate the liquor, and add to it 
acetate of lead, which immediately throws 
down the acid in the state of an igasurate of 
lead. This compound is then decomposed, 
by transmitting a current of sulphuretted 



hydrogen through it, diffused in eight or ten 
times its weight of boiling water. 

This acid, evaporated to ^he consistence of 
syrup, and left to itself, concretes in hard and 
granular crystals. It is very soluble in water 
and in alcohol. Its taste is acid and very 
styptic. It combines with the alkaline and 
earthy bases, forming salts soluble in water 
and alcohol. Its combination with baryta is 
very soluble, and crystallizes with difficulty, 
and mushroom-like. Its combination with 
ammonia, when perfectly neutral, does not 
form a precipitate with the salts of silver, 
mercury, and iron ; but it comports itself 
with the salts of copper in a peculiar man- 
ner, and which seems to characterize the 
acid of strychnos, (for the same acid is found 
in nux vomica, and in snake- wood, bois de 
couleuvre) : this effect consists in the decom- 
position of the salts of copper by its ammo- 
niacal compound. . These salts pass imme- 
diately to a green colour, and gradually 
deposit a greenish-white salt, of very sparing 
solubility in water. The acid of strychnos 
seems thus to resemble meconic acid ; but it 
differs essentially from it by its action with 
salts of iron, which immediately assume a 
very deep red colour with the meconic acid ; 
an effect not produced by the acid of strych- 
nos. The authors, after all, do not positively 
affirm this acid to be new and peculiar. 
Ann. de Chim. et de Phys. x. 14-2. 

ACID (INDIGOIC). This acid, first 
described by Chevreul, is distinct from the 
carbazotic acid, also procurable from indigo 
by the action of nitric acid. To obtain Chev- 
reul's acid, nitric acid sp. gr. 1.285, diluted 
with rather more than its weight of water, is 
heated in a retort, and small portions of in- 
digo, in fine powder, are added as long as 
any sensible effervescence is produced ; a lit- 
tle water being dropped in from time to time 
to prevent the formation of carbazotic acid. 
The yellow liquid is separated, while hot, 
from the resinous matter, and by cooling it 
deposits crystals of the acid of indigo. This 
was boiled with oxide of lead, filtered, and 
the salt present decomposed by sulphuric 
acid whilst hot ; on cooling, the liquor depo- 
sited the acid of indigo in yellowish-white 
crystals : these were separated, dissolved in 
hot water, neutralized by carbonate of ba- 
ryta, the solution concentrated, and allowed 
to cool ; yellow acicular crystals of a barytic 
salt were obtained, which being washed with 
cold water, dissolved in hot water, and de- 
composed by acids, gave acicular crystals of 
the acid of indigo, white as snow. They 
were collected and washed upon a filter. 
They shrunk into a small space when dry, 
losing almost entirely their crystalline aspect. 

This acid is white, with the lustre of silk : 
it has a weak acid bitter taste, reddens lit- 
mus, dissolves in any quantity in boiling 
water or alcohol, forming colourless solu- 



ACID 



57 



LACTIC. 



tions, but requires 1000 parts of cold water 
to dissolve it. It is volatile ; fusing and sub- 
liming without decomposition when heated 
in a tube. The fused acid, by cooling, crys- 
tallizes in six-sided plates. In the air it burns 
with a bright flame, evolving much smoke. 
Nitric acid converts it into a carbazotic acid. 
Neither chlorine gas, nor solution of chlo- 
rine, has any effect on it. It gives a blood- 
red colour to solutions of the peroxide salts 
of iron. When decomposed by heat and 
oxide of copper, it yields azote and carbonic 
acid in the same proportions as indigo itself. 
The constituents of the acid are, hydrogen 2, 
carbon 47, azote 7.3, oxygen 43.7, in 100 
parts. 100 parts of the acid combine with 
30 of baryta. 

ACID (IODO-SULPHURIC). When 
we pour sulphuric acid, drop by drop, into 
a concentrated and hot aqueous solution of 
iodic acid, there immediately results a preci- 
pitate of iodo-sulphuric acid, possessed of 
peculiar properties. Exposed gradually to 
the action of a gentle heat, the iodo-sulphu- 
ric acid melts, and crystallizes on cooling 
into rhomboids of a pale yellow colour. 
When strongly heated it sublimes, and is 
partially decomposed ; the latter portion be- 
ing converted into oxygen, iodine, and sul- 
phuric acid. 

Phosphoric and nitric acids exhibit similar 
phenomena. These compound acids act with 
great energy on the metals. They dissolve 
gold and platinum. 

ACID (IODIC). See p. 40. 
ACID (IODOUS). See p. 41. 
ACID (KINIC). A peculiar acid ex- 
tracted by M. Vauquelin from cinchona. 
Let a watery extract from hot infusions of 
the bark in powder be made. Alcohol re- 
moves the resinous part of this extract, and 
leaves a viscid residue, of a brown colour, 
which has hardly any bitter taste, and which 
consists of kinate of lime and a mucilaginous 
matter. This residue is dissolved in water, 
the liquor is filtered and left to spontaneous 
evaporation in a warm place. It becomes 
thick like syrup, and then deposits by degrees 
crystalline plates, sometimes hexaedral, some- 
times rhomboidal, sometimes square, and al- 
ways coloured slightly of a reddish-brown. 
These plates of kinate of lime must be puri- 
fied by a second crystallization. They are 
then dissolved in 10 or 12 times their weight 
of water, and very dilute aqueous oxalic acid 
is poured into the solution, till no more pre- 
cipitate is formed. By filtration the oxalate 
of lime is separated, and the kinic acid being 
concentrated by spontaneous evaporation, 
yields regular crystals. It is decomposed by 
heat. While it forms a soluble salt with 
lime, it does not precipitate lead or silver 
from their solutions. These are characters 
sufficiently distinctive. The kinates are 



scarcely known ; that of lime constitutes 7 
per cent of cinchona. 

ACID(KRAMERIC). A peculiar sub- 
stance, which M. Peschier of Geneva thought 
he had found in the root of the Kramer ia 
triandria. 

ACID (LACCIC) of Dr John. This 
chemist made a watery extract of powdered 
stick lac, and evaporated it to dryness. He 
digested alcohol on this extract, and evapo- 
rated the alcoholic extract to dryness. He 
digested this mass in ether, and evaporated 
the ethereal solution ; when he obtained a 
syrupy mass of a light yellow colour, which 
was again dissolved in alcohol. On add- 
ing water to this solution, a little resin 
fell. A peculiar acid united to potash and 
lime remains in the solution, which is ob- 
tained free, by forming with acetate of lead 
an insoluble laccate, and decomposing this 
with the equivalent quantity of sulphuric 
acid. Laccic acid crystallizes ; it has a wine- 
yellow colour, a sour taste, and is soluble, 
as we have seen, in water, alcohol, and ether. 
It precipitates lead and mercury white ; but 
it does not affect lime, baryta, or silver, in 
their solutions. It throws down the salts 
of iron white. With lime, soda, and potash, 
it forms deliquescent salts, soluble in al- 
cohol. 

ACID (LACTIC). The extract which 
is obtained when dried whey is digested with 
alcohol, contains uncotnbined lactic acid, lac- 
tate of potash, muriate of potash, and a pro- 
per animal matter. As the elimination of 
the acid affords an instructive example of 
chemical research, we shall present it at some 
detail from the 2d volume of Berzelius's Ani- 
mal Chemistry. 

He mixed the above alcoholic solution 
with another portion of alcohol, to which 7 ! j 
of concentrated sulphuric acid had been 
added, and continued to add fresh portions 
of this mixture as long as any saline preci- 
pitate was formed, and until the fluid had 
acquired a decidedly acid taste. Some sul- 
phate of potash was precipitated, and there 
remained in the alcohol, muriatic acid, lactic 
acid, sulphuric acid, and a minute portion of 
phosphoric acid, detached from some bone 
earth which had been held in solution. The 
acid liquor was filtered, and afterwards di- 
gested with carbonate of lead, which with the 
lactic acid affords a salt soluble in alcohol. 
As soon as the mixture had acquired a sweet- 
ish taste, the three mineral acids had fallen 
down in combination with the lead, and the 
lactic acid remained behind, imperfectly satu- 
rated by a portion of it, from which it was 
detached by means of sulphuretted hydro- 
gen, and then evaporated to the consistence 
of a thick varnish, of a dark brown colour 
and sharp acid taste, but altogether without 
smell. 



ACID 



58 



LITHIC. 



In order to free it from the animal matter 
which might remain combined with it, he 
boiled it with a mixture of a large quantity 
of fresh lime and water, so that the animal 
substances were precipitated and destroyed 
by the lime. The lime became yellow- 
brown, and the solution almost colourless, 
while the mass emitted a smell of soap lees, 
which disappeared as the boiling was con- 
tinued. The fluid thus obtained was filter- 
ed, and evaporated, until a great part of the 
superfluous lime held in solution was pre- 
cipitated. A small portion of it was then 
decomposed by oxalic acid, and carbonate of 
silver was dissolved in the uncombined lactic 
acid, until it was fully saturated. With the 
assistance of the lactate of silver thus obtain- 
ed, a farther quantity of muriatic acid was 
separated from the lactate of lime, which 
was then decomposed by pure oxalic acid, 
free from nitric acid, taking care to leave it 
in such a state that neither the oxalic acid 
nor lime water afforded a precipitate. It 
was then evaporated to dryness, and dissolved 
again in alcohol ; a small portion of oxalate 
of lime, before retained in union with the 
acid, now remaining undissolved. The alco- 
hol was evaporated until the mass was no 
longer fluid while warm ; it became a brown 
clear transparent acid, which was the lactic 
acid, free from all substances that we have 
hitherto had reason to think likely to conta- 
minate it. 

The lactic acid, thus purified, has a brown- 
yellow colour, and a sharp sour taste, which 
is much weakened by diluting it with water. 
It is without smell in the cold, but emits, 
when heated, a sharp sour smell, not unlike 
that of sublimed oxalic acid. It cannot be 
made to crystallize, and does not exhibit the 
slightest appearance of a saline substance, but 
dries into a thick and smooth varnish, which 
slowly attracts moisture from the air. It is 
very easily soluble in alcohol. Heated in a 
gold spoon over the flame of a candle, it 
first boils, and then its pungent acid smell 
becomes very manifest, but extremely dis- 
tinct from that of the acetic acid ; after- 
wards it is charred, and has an empyreu- 
matic, but by no means an animal smell. A 
porous charcoal is left behind, which does 
not readily burn to ashes. When distilled, 
it gives an empyreumatic oil, water, empy- 
reumatic vinegar, carbonic acid, and inflam- 
mable gases. With alkalis, earths, and me- 
tallic oxides, it affords peculiar salts : and 
these are distinguished by being soluble in 
alcohol, and in general by not having the 
least disposition to crystallize, but drying 
into a mass like gum, which slowly becomes 
moist in the air. 

Lactate of potash is obtained, when the 
lactate of lime, purified as has been men- 
tioned, is mixed with a warm solution of 
carbonate of potash. It forms, in drying, 



a gummy, light yellow-brown, transparent 
mass, which cannot easily be made hard. 

The lactate of soda resembles that of pot- 
ash, and can only be distinguished from it by 
analysis. 

Lactate of ammonia. If concentrated lac- 
tic acid is saturated with caustic ammonia in 
excess, the mixture acquires a strong volatile 
smell, not unlike that of the acetate or for- 
miate of ammonia, which, however, soon 
ceases. The salt which is left has sometimes 
a slight tendency to shoot into crystals. 

The lactate of baryta may be obtained in 
the same way as that of lime ; but it then con- 
tains an excess of the base. When evaporated 
it affords a gummy mass, soluble in alcohol. 

The lactate of lime is obtained in the man- 
ner above described. It affords a gummy 
mass, which is also divided by alcohol into 
two portions. 

Lactate of magnesia, evaporated to the con- 
sistence of a thin syrup, and left in a warm 
place, shoots into small granular crystals. 

The lactate of silver is procured by dis- 
solving the carbonate in the lactic acid. The 
solution is of a light yellow somewhat inclin- 
ing to green, and has an unpleasant taste of 
verdigris. 

The lactate of iron is of a red-brown co- 
lour, does not crystallize, and is not soluble 
in alcohol. The lactate of zinc crystallizes. 
Both these metals are dissolved by the lactic 
acid, with an extrication of hydrogen gas. 
The lactate of copper, according to its diffe- 
rent degrees of saturation, varies from blue 
to green and dark blue. It does not crys- 
tallize. 

It is only necessary to compare the de- 
scriptions of these salts with what we know 
of the salts which are formed with the same 
bases by other acids, for example, the acetic, 
the malic, and others, in order to be com- 
pletely convinced that the lactic acid must be a 
peculiar acid, perfectly distinct from all others. 
Its prime equivalent may be called 5.8. 

The nanceic acid of Braconnot resembles 
the lactic in many respects. 

ACID (LITHIC). Lithate of potash is 
obtained by digesting human urinary calculi 
in caustic lixivium ; and Fourcroy recom- 
mends the precipitation of the lithic acid from 
this solution by acetic acid, as a good process 
for obtaining the acid pure, in small, white, 
shining, and almost pulverulent needles. 

It has the form of white shining plates, 
which are denser than water. Has no taste 
nor smell. It dissolves in about 1400 parts 
of boiling water. It reddens the infusion of 
litmus. When dissolved in nitric acid, and 
evaporated to dryness, it leaves a pink sedi- 
ment. The dry acid is not acted on nor dis- 
solved by the alkaline carbonates or sub-car- 
bonates. It decomposes soap when assisted 
by heat ; as it does also the alkaline sul- 
phurets and hydrosulphurets. No acid acts 



ACID 



MANGANESIC. 



on it, except those that occasion its decom- 
position. It dissolves in hot solutions of 
potash and soda, and likewise in ammonia, 
but less readily. The lithates may be formed, 
either by mutually saturating the two con- 
stituents, or we may dissolve the acid in an 
excess of base, and we may then precipitate 
by carbonate of ammonia. The lithates are 
all tasteless, and resemble in appearance lithic 
acid itself. They are not altered by exposure 
to the atmosphere. They are very sparingly 
soluble in water. They are decomposed by 
a red heat, which destroys the acid. The 
lithic acid is precipitated from these salts by 
all the acids, except the prussic and carbonic. 
They are decomposed by the nitrates, muri- 
ates, and acetates of baryta, strontia, lime, 
magnesia, and alumina. They are precipi- 
tated by all the metallic solutions, except that* 
of gold. When lithic acid is exposed to heat, 
the products are, carburetted hydrogen and 
carbonic acid, prussic acid, carbonate of am- 
monia, a sublimate consisting of ammonia 
combined with a peculiar acid, which has the 
following properties : 

Its colour is yellow, and it has a cooling 
bitter taste. It dissolves readily in water, 
and in alkaline solutions, from which it is not 
precipitated by acids. It dissolves also spar- 
ingly in alcohol. It is volatile, and when sub- 
limed a second time, becomes much whiter. 
The watery solution reddens vegetable blues ; 
but a very small quantity of ammonia de- 
stroys this property. It does not cause effer- 
vescence with alkaline carbonates. By eva- 
poration it yields permanent crystals, but ill 
defined, from adhering animal matter. These 
redden vegetable blues. Potash, when added 
to these crystals, disengages ammonia. When 
dissolved in nitric acid, they do not leave a 
red stain, as happens with uric acid ; nor 
does their solution in water decompose the 
earthy salts, as happens with alkaline lithates 
(or urates). Neither has it any action on 
the salts of copper, iron, gold, platinum, tin, 
or mercury. With nitrates of silver and 
mercury, and acetate of lead, it forms a white 
precipitate, soluble in an excess of nitric acid. 
Muriatic acid occasions no precipitate in the 
solution of these crystals in water. These 
properties show, that the acid of the sub- 
limate is different from the uric, and from 
every other known acid. Dr Austin found, 
that by repeated distillations lithic acid was 
resolved into ammonia, nitrogen, and prussic 
acid. See ACID (PYROLITHIC). 

When lithic acid is projected into a flask 
with chlorine, there is formed, in a little time, 
muriate of ammonia, oxalate of ammonia, 
carbonic acid, muriatic acid, and malic acid : 
the same results are obtained by passing 
chlorine through water holding this acid in 
suspension. 

M. Gay Lussac mixed lithic acid with 20 
times its weight of oxide of copper, put the 



mixture into a glass tube, and covered it with 
a quantity of copper filings. The copper fil- 
ings being first heated to a dull red, heat was 
applied to the mixture. The gas which came 
over was composed of 0.69 carbonic acid, 
and 0.31 nitrogen. He conceives, that the 
bulk of the carbonic acid would have been 
exactly double that of the nitrogen, had it 
not been for the formation of a little carbo- 
nate of ammonia. Hence, uric acid contains 
two prime equivalents of carbon, and one of 
nitrogen. This is the same proportion as 
exists in cyanogen. Probably a prime equi- 
valent of oxygen is present. Dr Prout, in 
the eighth vol. of the Med. Chir. Trans, de- 
scribes the result of an analysis of lithic acid, 
effected also by ignited oxide of copper, but 
so conducted as to determine the product of 
oxygen and hydrogen. Four grains of lithic 
acid yielded, water 1.05, carbonic acid 11.0 
c. inches, nitrogen 5.5. ditto. Hence, it con- 
sisted of 

Hydrogen, 2.857 or 1 prime = 0. 125 
Carbon, 34286 2 =1.500 

Oxygen, 22.857 1 =1.000 

Nitrogen, 40.00 1 =1.750 

100.000 4.375 

M. Berard has published an analysis of 

lithic acid since Dr Prout, in which he also 

employed oxide of copper. 

The following are the results : 

Carbon, 33.61^ C I Carbon. 

Oxygen, 18. 89 which ap-j 1 Oxygen. 

Hydrogen, 8.34fproach to 1 4 Hydrogen. 

Nitrogen, 39.16J C 1 Nitrogen. 



100.00 

Here we find the nitrogen and carbon 
nearly in the same quantity as by Dr Prout; 
but there is much more hydrogen and less 
oxygen. By urate of baryta, we have the 
prime equivalent of uric acid equal to 15.67 ; 
and by urate of potash it appears to be 14.0. 
It is needless to try to accommodate an ar- 
rangement of prime equivalents to these dis- 
crepancies. The lowest number would re- 
quire, on the Daltonian plan, an association 
of more than twenty atoms, the grouping of 
which is rather a sport of fancy than an exer- 
cise of reason : For what benefit could ac- 
crue to chemical science by stating, that if 
we consider the atom of lithic acid to be 
16.75, then it would probably consist of 

7 atoms Carbon, =5.25 31 A 

3 Oxygen, = 3.00 17.90 
12 Hydrogen, = 1.500 8.90 

4 Nitrogen, =7.00 41.80 

26 16.75 100.0 

ACID (MANGANESIC). Whenman- 
ganesate of potash (cameleon mineral) is dis- 
tilled with a little anhydrous sulphuric acid, 
manganesic acid is evolved in the form of a 
red transparent gas, which dissolves in water, 



ACID 



60 



MALIC. 



forming a red solution. The gas frequently 
decomposes spontaneously in the retort with 
explosion, producing oxide of manganese and 
oxygen. 

Manganesate of potash was analyzed by 
distilling it with excess of sulphuric acid, col- 
lecting the oxygen disengaged, and estimat- 
ing the proportion of protoxide of manganese 
and salts of potash remaining in the retort. 
According to these experiments, the acid 
consists of 

Manganese, 58.74 

Oxygen, 41.26 

100.00 

And the manganesate of potash calcined 

Potash, 25.63 32.75 

Manganesic acid, 52.44 67.25 

Water, 21.93 

100.00 

100.00 

ACID (MALIC). The acid of apples, 
called malic, may be obtained most conve- 
niently and in greatest purity from the berries 
of the mountain-ash, called sorbus or pyrus 
aucuparia, and hence it has been called sor- 
bic acid. This was supposed to be a new 
and peculiar acid by Mr Donovan and M. 
Vauquelin, who wrote full dissertations upon, 
it. But it now appears that the sorbic and 
pure malic acids are identical. 

Bruise the ripe berries in a mortar, and 
then squeeze them in a linen bag. They 
yield nearly half their weight of juice, of the 
specific gravity of 1.077. This viscid juice, 
by remaining for about a fortnight in a warm 
temperature, experiences the vinous fermen- 
tation, and would yield a portion of alcohol. 
By this change, it has become bright, clear, 
and passes easily through the filter, while the 
sorbic acid itself is not altered. Mix the 
clear juice with filtered solution of acetate of 
lead. Separate the precipitate on a filter, 
and wash it with cold water. A large quan- 
tity of boiling water is then to be poured 
upon the filter, and allowed to drain into 
glass jars. At the end of some hours the 
solution deposits crystals of great lustre and 
beauty. Wash these with cold water, dis- 
solve them in boiling water, filter, and crys- 
tallize. Collect the new crystals, and boil 
them for half an hour in 2.3 times their 
weight of sulphuric acid, specific gravity 
1.090, supplying water as fast as it evapo- 
rates, and stirring the mixture diligently with 
a glass rod. The clear liquor is to be de- 
canted into a tall narrow glass jar, and, while 
still hot, a stream of sulphuretted hydrogen 
is to be passed through it. When the lead 
has been all thrown down in a sulphuret, the 
liquid is to be filtered, and then boiled in an 
open vessel to dissipate the adhering sulphu- 
retted hydrogen. It is now a solution of 
sorbic acid. 



When it is evaporated to the consistence 
of a syrup, it forms mammelated masses of a 
crystalline structure. It still contains a con- 
siderable quantity of water, and deliquesces 
when exposed to the air. Its solution is trans- 
parent, colourless, void of smell, but power- 
fully acid to the taste. Lime and baryta 
waters are not precipitated by solution of the 
sorbic acid, although the sorbate of lime is 
nearly insoluble. One of the most charac- 
teristic properties of this acid is the precipi- 
tate which it gives with the acetate of lead, 
which is at first white and flocculent, but 
afterwards assumes a brilliant crystalline ap- 
pearance. With potash, soda, and ammonia, 
it forms crystallizable salts containing an ex- 
cess of acid. That of potash is deliquescent. 
Sorbate of baryta consists, according to M. 
Vauquelin, of 47 sorbic acid, and 53 baryta, 
in 100. Sorbate of lime well dried, appeared 
to be composed of 67 acid + 33 lime = 100. 
Sorbate of lead, which in solution, like most 
of the other sorbates, retains an acidulous 
taste, consists in the dried state of 33 acid -f- 
67 oxide of lead in 100. The ordinary sor- 
bate contains 12.5 per cent of water. M. 
Vauquelin says that Mr Donovan was mis- 
taken in supposing that he had obtained super 
and sub-sorbates of lead. There is only one 
salt with this base, according to M. Vau- 
quelin. It is nearly insoluble in cold water, 
but a little more so in boiling water : as it 
cools, it crystallizes in the beautiful white, 
brilliant, and shining needles, of which we 
have already spoken. A remarkable pheno- 
menon occurs when sorbate of lead is boiled 
in water. Whilst one part of the salt satu- 
rates the water, the other part, for want of a 
sufficient quantity of fluid to dissolve it, is 
partially melted, and is at first kept on the 
surface by the force of ebullition, but after 
some time falls to the bottom, and as it cools 
becomes strongly fixed to the vessel. 

To procure malic acid, M. Braconnot sa- 
turates with chalk the juice of the scarcely 
ripe berries, evaporates to the consistence of 
a syrup, removing the froth ; and a granular 
sorbate falls, which he decomposes by car- 
bonate of soda. The sorbate of soda is freed 
from colouring matter by a little lime, strain- 
ed, freed from lime by carbonic acid gas, and 
decomposed by subacetate of lead, and treated 
as above. 

M. Vauquelin analyzed the acid in the 
dry malates of copper and lead. 

The following are its constituents : 
Hydrogen, 16.8 
Carbon, 28.3 
Oxygen, 54.9 

100.0 

M. Vauquelin's analysis of the malate of 
lead gives 7.0 for the prime equivalent of this 
acid; the sorbate of lime gives 7.230; and 
the sorbate of baryta 8.6. 



ACID 



MECONIC. 



The calcareous salt having been procured 
in a neutral state, by the addition of carbonate 
of potash to its acidulous solution, it might 
readily be mixed with as much carbonate of 
lime as would diminish the apparent equiva- 
lent of acid from 7.50 to 7.230 ; especially as 
the barytic compound gives no less than 8.6. 
Had the composition of the malate of lime 
been 67.7 and 32.3, instead of 67 and 33, 
the prime equivalent of the acid would come 
out 7.5, as its ultimate analysis indicates. 
Dr Prout's analysis of malic acid gives, 

Carbon, 40.68 

Water, 45.76 

Oxygen, 13.56 

JOO.OO 

As the pure malic acid appears to be with- 
out odour, without colour, and of an agree- 
able taste, it might be substituted for the tar- 
taric and citric, in medicine and the arts. 

The same acid may be got from apples, in 
a similar way. 

ACID (MARGARIC). When we im- 
merse soap made of pork-grease and potash 
in a large quantity of water, one part is dis- 
solved, while another part is precipitated in 
the form of several brilliant pellets. These 
are separated, dried, washed in a large quan- 
tity of water, and then dried on a filter. They 
are now dissolved in boiling alcohol, sp. gr. 
0.820, from which, as it cools, the pearly sub- 
stance falls down pure. On acting on this 
with dilute muriatic acid, a substance of a 
peculiar kind, which M. Chevreul, the dis- 
coverer, calls margarine, or margaric acid, is 
separated. It must be well washed with 
water, dissolved in boiling alcohol, from 
which it is recovered in the same crystalline 
pearly form when the solution cools. 

Margaric acid is pearly white, and taste- 
less. Its smell is feeble, and a little similar 
to that of melted wax. Its specific gravity is 
inferior to water. It melts at 134 F. into 
a very limpid colourless liquid, which crys- 
tallizes, on cooling, into brilliant needles of 
the finest white. It is insoluble in water, but 
very soluble in alcohol, sp. gr. 0.800. Cold 
margaric acid has no action on the colour of 
litmsis ; but when heated so as to soften with- 
out melting, the blue was reddened. It com- 
bines with the salifiable bases, and forms neu- 
tral compounds. 100 parts of it unite to a 
quantity of base containing three parts of 
oxygen, supposing that 100 of potash contain 
1 7 of oxygen. Two ordei-s of margarates are 
formed, the margarates and the supermarga- 
rates; the former being converted into the 
latter by pouring a large quantity of water 
on them. Other fats besides that of the hog 
yield this substance. 

Acid. Base. 

Margarate of potash consists of 100 17.77 
Supermargarate, - - 100 8.88 
Margarate of soda, - - 100 12.72 



Acid. Base. 

Baryta, - 100 28.93 

Strontia, - '-; , - 100 20.23 
Lime, - - - v - 100 11.06 

Potash. 

Supermargarate of Human fat, 100 8.85 
Sheep fat, 100 8.68 
Ox fat, 100 8.78 
Jaguar fat, 100 8.60 
Goose fat, 100 8.77 
If we compare the above numbers, we shall 
find 35 to be the prime equivalent of mar- 
garic acid. 

That of man is obtained under three dif- 
ferent forms. 1st, In very fine long needles, 
disposed in flat stars. 2d, In very fine and 
very short needles, forming waved figures, like 
those of the margaric acid of carcasses. 3d, 
In very large brilliant crystals disposed in 
stars, similar to the margaric acid of the hog. 
The margaric acids of man and the hog re- 
semble each other; as do those of the ox and 
the sheep ; and of the goose and the jaguar. 
The compounds with the bases are real soaps. 
The solution in alcohol affords the transpa- 
rent soap of this country. Ann. de Chimie 
et de Phys. several volumes. 

ACID (MECONIC). This acid is a con- 
stituent of opium. It was discovered by M. 
Sertuerner, who procured it in the following 
way : After precipitating the morphia from 
a solution of opium by ammonia, he added 
to the residual fluid a solution of the muriate 
of baryta. A precipitate is in this way 
formed, which is supposed to be a quadruple 
compound, of baryta, morphia, extract, and 
the meconic acid. The extract is removed 
by alcohol, and the baryta by sulphuric acid, 
when the meconic acid is left merely in com- 
bination with a portion of the morphia ; and 
from this it is purified by successive solutions 
and evaporations. The acid, when sublimed, 
forms long colourless needles ; it has a strong 
affinity for the oxide of iron, so as to take it 
from the muriatic solution, and form with it 
a cherry-red precipitate. It forms a crystal- 
lizable salt with lime, which is not decom- 
posed by sulphuric acid ; and what is curious, 
it seems to possess no particular power over 
the human body, when received into the sto- 
mach. The essential salt of opium, obtained 
in M. Derosne's original experiments, was 
probably the meconiate of morphia. 

M. Robiquet has made a useful modifica- 
tion of the process for extracting meconic 
acid. He treats the opium with magnesia, 
to separate the morphia, while meconiate of 
magnesia is also formed. The magnesia is 
removed by adding muriate of baryta, and 
the baryta is afterwards separated by dilute 
sulphuric acid. A larger proportion of me- 
conic acid is thus obtained. 

M. Robiquet denies that meconic acid 
precipitates iron from the muriate; but, ac- 
cording to M. Vogel, its power of reddening 



ACID 



MELLITIC. 



solutions of iron is so great, as to render it a 
more delicate test of this metal than even 
the ferrocyanate of potash. 

To obtain pure meconic acid from the me- 
coniate of baryta, M. Choulant triturated it 
in a mortar with its own weight of glassy 
boracic acid. This mixture being put into a 
small glass flask, which was surrounded with 
sand in a sand pot in the usual manner, and 
the red heat being gradually raised, the me- 
conic acid sublimed in the state of fine white 
scales or plates. It has a strong sour taste, 
which leaves behind it an impression of bitter- 
ness. It dissolves readily in water, alcohol, 
and ether. It reddens the greater number 
of vegetable blues, and changes the solutions 
of iron to a cherry-red colour. When these 
solutions are heated, the iron is precipitated 
in the state of protoxide. 

The meconiates examined by Choulant are 
the following: 

1st, Meconiate of potash. It crystallizes 
in four- sided tables, is soluble in twice its 
weight of water, and is composed of 

Meconic acid, 27 2.7 

Potash, 60 6.0 

Water, 13 

100 

It is destroyed by heat. 
2d, Meconiate of soda. It crystallizes in 
soft prisms, is soluble in fives times its weight 
of water, and seems to effloresce. It is de- 
stroyed by heat. It consists of 

Acid, 32 3.2 

Soda, 40 4.6 

Water, 28 

100 

3d, Meconiate of ammonia. It crystallizes 
in star-form needles, which, when sublimed, 
lose their water of crystallization, and as- 
sume the shape of scales. The crystals are 
soluble in 1^ their weight of water, and are 
composed of 

Acid, 40 2.03 

Ammonia, 42 2. 13 

Water, 18 

100 

If two parts of sal ammoniac be triturated 
with three parts of meconiate of baryta, and 
heat be applied to the mixture, meconiate of 
ammonia sublimes, and muriate of baryta 
remains. 

4>th, Meconiate of lime. It crystallizes in 
prisms, and is soluble in eight times its 
weight of water. It consists of 

Acid, 34 2.882 

Lime, 42 3.560 

Water, 24 

100 

As the potash and lime compounds give 
nearly the same acid ratio, we may take their 
mean of it as the true prime = 2.8. 



To procure meconiate of morphia, says 
Dr Giuseppe Meneci, reduce good opium to 
powder, put it into a paper filter, add dis- 
tilled water to it, and slightly agitate it. In 
this way wash it, till the water passes through 
colourless ; then pass a little diluted alcohol 
through it; dry the insoluble portion (now 
diminished to one-half) in a dark place ; di- 
gest it when dry in strong alcohol for a few 
minutes, applying heat; separate the solu- 
tion, which, by cooling and after evapora- 
tion, will yield well crystallized meconiate of 
morphia of a pale straw colour. Giorn. di 
Fisica, vii. 218. 

ACID (MEL ASSIC). The acid present 
in melasses, which has been thought a pecu- 
liar acid by some, by others the acetic. 

ACID (MELLITIC). M. Klaproth dis- 
covered in the melilite, or honey-stone, what 
he conceives to be a peculiar acid of the ve- 
getable kind, combined with alumina. This 
acid is easily obtained by reducing the stone 
to powder, and boiling it in about 70 times 
its weight of water ; when the acid will dis- 
solve, and may be separated from the alumina 
by filtration. By evaporating the solution, 
it may be obtained in the form of crystals. 
The following are its characters : 

It crystallizes in fine needles or globules 
by the union of these, or small prisms. Its 
taste is at first a sweetish sour, which leaves 
a bitterness behind. On a plate of hot metal 
it is readily decomposed, and dissipated in 
copious' grey fumes, which affect not the 
smell, leaving behind a small quantity of 
ashes, that do not change either red or blue 
tincture of litmus. Neutralized by potash it 
crystallizes in groups of long prisms; by 
soda, in cubes, or triangular liminae, some- 
times in groups, sometimes single; and by 
ammonia, in beautiful prisms with six planes, 
which soon lose their transparency, and ac- 
quire a silvery-white hue. If the mellitic 
acid be dissolved in lime water, and a solu- 
tion of calcined strontia or baryta be drop- 
ped into it, a white precipitate is thrown 
down, which is redissolved on adding mu- 
riatic acid. With a solution of acetate of 
baryta it produces likewise a white precipi- 
tate, which nitric acid redissolves. With so- 
lution of muriate of baryta it produces no 
precipitate, or even cloud ; but after standing 
some time, fine transparent needley crystals 
are deposited. The mellitic acid produces 
no change in a solution of nitrate of sil- 
ver. From a solution of nitrate of mer- 
cury, either hot or cold, it throws down a 
copious white precipitate, which an addition 
of nitric acid immediately redissolves. With 
nitrate of iron it gives an abundant precipi- 
tate of a dun yellow colour, which may be 
redissolved by muriatic acid. With a solu- 
tion of acetate of lead it produces an abun- 
dant precipitate, immediately redissolved on 
adding nitric acid. With acetate of copper 
it gives a greyish-green precipitate ; but it 



ACID 



63 



MOROXYLIC. 



does not affect a solution of muriate of cop- 
per. Lime water precipitated by it is im- 
mediately redissolved on adding nitric acid. 

M. Klaproth was never able to convert 
this acid into the oxalic by means of nitric 
acid, which only changed its brownish colour 
to a pale yellow. 

The mellite, or native mellate of alumina, 
consists, according to Klaproth, of 46 acid -|- 
16 alumina + 38 water = 100 ; from which, 
calling the prime of alumina 2.25, that of 
mellitic acid appears to be 6.5. 

ACID (MENISPERMIC). M. Casa- 
seca has published, in the 30th vol. of the 
Ann. de Chim. et de Phys. a Memoir on 
Menispermum Cocculus, in which he de- 
monstrates, 

1. That menispermic acid does not exist. 

2. That picrotoxia does not possess alka- 
line properties, and ought not to be consi- 
dered as a new vegetable salifiable base, but 
merely as a peculiar bitter principle, as M. 
Boullay announced it in his first paper. 

ACID (MOLYBDIC). The native sul- 
phuret of molybdenum being roasted for some 
time, and dissolved in water of ammonia, 
when nitric acid is added to this solution, the 
molybdic acid precipitates in fine white scales, 
which become yellow on melting and sub- 
liming them. It changes the vegetable blues 
to red, but less readily and powerfully than 
the molybdous acid. 

M. Bucholz found, that 100 parts of the 
sulphuret gave 90 parts of molybdic acid. 
In other experiments in which he oxidized 
molybdenum, he found that 100 of the metal 
combined with from 49 to 50 of oxygen. 
Berzelius, after some vain attempts to analyze 
the molybdates of lead and baryta, found 
that the only method of obtaining an exact 
result was to form a molybdate of lead. He 
dissolved 10 parts of neutral nitrate of lead 
in water, and poured an excess of solution of 
crystallized molybdate of ammonia into the 
liquid. The molybdate of lead, washed, 
dried, and heated to redness, weighed 1 1.068. 
No traces of lead were found in the liquid by 
sulphate of ammonia : hence these 1 1.068 of 
lead, evince 67.3 per cent of oxide of lead. 
This salt then is composed of 

Molybdic acid, 39.194 9.0 
Oxide of lead, 60.806 14.0 

100.000 

And from Bucholz we infer, that this prime 
equivalent 9 consists of 3 of oxygen -f- 6 me- 
tal ; while molybdous acid will be 2 oxygen 
-f 6 metal = 8.0. 

Molybdic acid has a specific gravity of 
3.460. In an open vessel it sublimes into 
brilliant yellow scales ; 960 parts of boiling 
water dissolve one of it, affording a pale yel- 
low solution, which reddens litmus, but has 
no taste. Sulphur, charcoal, and several me- 
tals decompose the molybdic acid. Molybdate 



of potash is a colourless salt. Molybdic acid 
gives, with a nitrate of lead, a white precipi- 
tate, soluble in nitric acid ; with the nitrates 
of mercury and silver, a white flaky precipi- 
tate ; with nitrate of copper, a greenish pre- 
cipitate : with solutions of the neutral sul- 
phate of zinc, muriate of bismuth, muriate of 
antimony, nitrate of nickel, muriates of gold 
and platinum, it produces white precipitates. 
When melted with borax, it yields a bluish 
colour ; and paper dipped in its solution be- 
comes, in the sun, of a beautiful blue. 

The neutral alkaline molybdates precipi- 
tate all metallic solutions. Gold, muriate of 
mercury, zinc, and manganese, are precipi- 
tated in the form of a white powder ; iron 
and tin, from their solutions in muriatic acid, 
of a brown colour; cobalt, of a rose colour; 
copper, blue; and the solutions of alum and 
quicklime, white. If a dilute solution of re- 
cent muriate of tin be precipitated by a dilute 
solution of molybdate of potash, a beautiful 
blue powder is obtained. 

The concentrated sulphuric acid dissolves 
a considerable quantity of the molybdic acid, 
the solution becoming of a fine blue colour 
as it cools, at the same time that it thickens : 
the colour disappears again on the application 
of heat, but returns again by cooling. A 
strong heat expels the sulphuric acid. The 
nitric acid has no effect on it ; but the mu- 
riatic dissolves it in considerable quantity, and 
leaves a dark blue residuum when distilled. 
With a strong heat it expels a portion of sul- 
phuric acid from sulphate of potash. It also 
disengages the acid from nitre and common 
salt by distillation. It has some action upon 
the filings of the metals in the moist way. 

The molybdic acid has not yet been em- 
ployed in the arts. 

ACID (MOLYBDOUS). The deut- 
oxide of molybdenum is of a blue colour, and 
possesses acid properties. Triturate 2 parts 
of molybdic acid with 1 part of the metal, 
along with a little hot water, in a porcelain 
mortar, till the mixture assumes a blue co- 
lour. Digest in 10 parts of boiling water, 
filter, and evaporate the liquid in a heat of 
about 120. The blue oxide separates. It 
reddens vegetable blues, and forms salts with 
the bases. Air or water, when left for some 
time to act on molybdenum, converts it into 
this acid. It consists of about 100 metal to 
34 oxygen. 

ACID (MORIC). See ACID (MOR- 
OXYLIC). 

ACID (MOROXYLIC). In the bo- 
tanic garden at Palermo, Mr Thomson found 
an uncommon saline substance on the trunk 
of a white mulberry tree. It appeared as a 
coating on the surface of the bark, in little 
granulous drops of a yellowish and blackish- 
brown colour, and had likewise penetrated its 
substance. M. Klaproth, who analyzed it, 
found that its taste was somewhat like that of 



ACID 



MURIATIC. 



succinic acid : on burning coals it swelled 
up a little, emitted a pungent vapour scarcely 
visible to the eye, and left a slight earthy re- 
siduum. Six hundred grains of the bark 
loaded with it were lixiviated with water, and 
afforded 320 grains of a light salt, resembling 
in colour a light wood, and composed of 
short needles united in radii. It was not 
deliquescent; and though the crystals did 
not form till the solution was greatly con- 
densed by evaporation, it is not very soluble, 
since 1000 parts of water dissolve but 35 
with heat, and ]5 in the cold. 

This salt was found to be a compound of 
lime and a peculiar vegetable acid, with some 
extractive matter. 

To obtain the acid separate, M. Klaproth 
decomposed the calcareous salt by acetate of 
lead, and separated the lead by sulphuric 
acid. He likewise decomposed it directly by 
sulphuric acid. The product was still more 
like succinic acid in taste ; was not deliques- 
cent; easily dissolved both in water and al- 
cohol; and did not precipitate the metallic 
solutions, as it did in combination with lime. 
Twenty grains being slightly heated in a 
small glass retort, a number of drops of an 
acid liquor first came over ; next a concrete 
salt arose, that adhered flat against the top 
and part of the neck of the retort, in the form 
of prismatic crystals, colourless and trans- 
parent ; and a coaly residuum remained. The 
acid was then washed out, and crystallized by 
spontaneous evaporation. Thus sublimation 
appears to be the best mode of purifying the 
salt, but it adhered too strongly to the lime 
to be separated from it directly by heat with- 
out being decomposed. 

Not having a sufficient quantity to deter- 
mine its specific characters, though he con- 
ceives it to be a peculiar acid, coming nearest 
to the succinic both in taste and other quali- 
ties, M. KlapYoth has provisionally given it 
the name of moroxylic, and the calcareous 
salt containing it that of moroxylate of lime. 

ACID (MUCIC). This acid has been 
generally known by the name of saccholactic, 
because it was first obtained from sugar of 
milk ; but all the gums appear to afford it. 
Though it is still principally made from su- 
gar of milk, chemists in general distinguish 
it by the name of mucic acid. 

It was discovered by Scheele. Having 
poured twelve ounces of diluted nitric acid on 
four ounces of powdered sugar of milk in a 
glass retort on a sand bath, the mixture be- 
came gradually hot, and at length effervesced 
violently, and continued to do so for a con- 
siderable time after the retort was taken from 
the fire. It is necessary therefore to use a 
large retort, and not to lute the receiver too 
tight. The effervescence having nearly sub- 
sided, the retort was again placed on the sand 
heat, and the nitric acid distilled off, till the 
mass had acquired a yellowish colour. This 



exhibiting no crystals, eight ounces more of 
the same acid were added, and the distillation 
repeated, till the yellow colour of the fluid 
disappeared. As the fluid was inspissated 
by cooling, it was redissolved in eight ounces 
of water, and filtered. The filtered liquor 
held oxalic acid in solution, and seven drams 
and a half of white powder remained on the 
filter. This powder was the acid under con- 
sideration. 

If one part of gum be heated gently with 
two of nitric acid, till a small quantity of ni- 
trous gas and of carbonic acid is disengaged, 
the dissolved mass will deposit, on cooling, 
the mucic acid. According to Fourcroy and 
Vauquelin, different gums yield from 14> to 
26 hundredths of this acid. 

This pulverulent acid is soluble in about 
60 parts of hot water, and by cooling, a fourth 
part separates in small shining scales, that 
grow white in the air. It decomposes the 
muriate of baryta, and both the nitrate and 
muriate of lime. It acts very little on the 
metals, but forms with their oxides salts 
scarcely soluble. It precipitates the nitrates 
of silver, lead, and mercury. With potash it 
forms a salt soluble in eight parts of boiling 
water, and crystallizable by cooling. That of 
soda requires but five parts of water, and is 
equally crystallizable. Both these salts are 
still more soluble whep the acid is in excess. 
That of ammonia is deprived of its base by 
heat. The salts of baryta, lime, and mag- 
nesia, are nearly insoluble. 

Mucic or saccholactic acid has been ana- 
lyzed recently with much care : 

Hydrogen. Carbon. Oxygen. 
ByLussac, 3.62 +33.69 +62.69 =100 

Berzelius, 5. 105+33. 430-f 61.465= 100 

From saclactate of lead Berzelius has in- 
ferred the prime equivalent of the acid to be 
13.1. 

ACID (MURIATIC). The HYDRO- 
CHLORIC of the French chemists. Let six 
parts of pure and well dried sea salt be put 
into a glass retort, to the beak of which is 
luted, in a horizontal direction, a long glass 
tube artificially refrigerated, and containing 
a quantity of ignited muriate of lime. Upon 
the salt pour at intervals five parts of concen- 
trated oil of vitriol, through a syphon funnel 
fixed air-tight in the tubulure of the retort. 
The free end of the long tube being recurv- 
ed, so as to dip into the mercury of a pneu- 
matic trough, a gas will issue, which, on 
coming in contact with the air, will form a 
visible cloud, or haze, presenting, when 
viewed in a vivid light, prismatic colours. 
This gas is muriatic acid. 

When received in glass jars over dry mer- 
cury, it is invisible, and possesses all the me- 
chanical properties of air. Its odour is pun- 
gent and peculiar. Its taste acid and corro- 
sive. Its specific gravity, according to Sir 
H. Davy, is such, that 100 cubic inches weigh 



ACID 



MURIATIC. 



39 grains, while by estimation, he says, they 
ought to be 38.4 gr. By the latter number 
the specific gravity, compared to air, becomes 
1.2590. By the former number the density 
comes out 1.2800. M. Gay Lussac states 
thesp. gr. at 1.2780. Sir H.'s second num- 
ber makes the prime equivalent of chlorine 
4.43, which comes near to Berzelius's latest 
result; while his first number makes it 4.48. 
(See CHLORINE.) As the attraction of mu- 
riatic acid gas for hygrometric water is very 
strong, it is very probable that 38.4 grs. may 
be the more exact weight of 100 cubic inches, 
regarding the same bulk of air as = 30.5. 
(See the Table of GASES.) If an inflamed 
taper be immersed in it, it is instantly extin- 
guished. It is destructive of animal life; 
but the irritation produced by it on the epi- 
glottis scarcely permits its descent into the 
lungs. It is merely changed in bulk by al- 
terations of temperature; it experiences no 
change of state. 

By sealing up muriate of ammonia and 
sulphuric acid in a strong glass tube recurv- 
ed, and causing them to act on each other, 
Sir H. Davy procured liquid muriatic acid. 
He justly observes, that the generation of 
elastic substances in close vessels, either 
with or without heat, offers much more 
powerful means of approximating their mole- 
cules than those dependent on the application 
of cold, whether natural or artificial ; for as 
diminish only ? i^ in volume for every 
of Fahrenheit's scale, beginning at 
ordinary temperature, a very slight conden- 
sation only can be produced by the most 
powerful freezing mixtures, not half as much 
as would result from the application of a 
strong flame to one part of a glass tube, the 
other part being of ordinary temperature : 
and when attempts are made to condense 
gases into liquids by sudden mechanical 
compression, the heat instantly generated 
presents a formidable obstacle to the success 
of the experiment ; whereas in the compres- 
sion resulting from their slow generation in 
close vessels, if the process be conducted 
with common precautions, there is no source 
of difficulty or danger ; and it may be easily 
assisted by artificial cold, in cases where gases 
approach near to that point of compression 
and temperature at which they become va- 
pours Phil Trans. 1823. 

When potassium, tin, or zinc, is heated in 
contact with this gas over mercury, one-half 
of the volume disappears, and the remainder 
is pure hydrogen. On examining the solid 
residue, it is found to be a metallic chlorine. 
Hence muriatic acid gas consists of chlorine 
and hydrogen, united in equal volumes. This 
view of its nature was originally given by 
Scheele, though obscured by terms derived 
from the vague and visionary hypothesis of 
phlogiston. The French school afterwards 
introduced the belief that muriatic acid gas 



was a compound of an unknown radical and 
water; and that chlorine consisted of this 
radical and oxygen. Sir H. Davy has the 
distinguished glory of refuting that hypo- 
thesis, and of proving, by decisive experi- 
ments, that, in the present state of our know- 
ledge, chlorine must be regarded as a simple 
substance, and muriatic acid gas as a com- 
pound of it with hydrogen. 

The gaseous acid unites rapidly, and in 
large quantity, with water. The following 
table of its aqueous combinations was con- 
structed after experiments made by Mr E. 
Davy, in the laboratory of the Royal Insti- 
tution, under the inspection of Sir H. Davy. 

At temperature 45, barometer 30, 



water, 


of specific gra- 


gas, parts, 


vity 


1.21 contain 


42.43 




1.20 


40.80 




1.19 


38.38 




1.17 


34.34 


. 


1.16 


32.32 




1.15 


30.30 




1.14 


28.28 




1.13 


26.26 




1.12 


24.24 




l.ll 


22.30 




1.10 


20.20 




1.09 


18.18 




1.08 


16.16 




1.07 


14.14 




1.06 


12.12 




1.05 


10.10 




1.04 


8.08 




1.03 


6.06 




1.02 


4.04 




1.01 


2.02 



At the temperature of 40 Fahrenheit, 
water absorbs about 480 times its bulk of 
gas, and forms solution of muriatic acid gas 
in water, the specific gravity of which is 
1.2109 Sir H. Davy's Elements. 

In the Annals of Philosophy for October 
and November 1817, there are two papers 
on the constitution of liquid muriatic acid, 
with tables, by myself, which coincide nearly 
with the preceding results. They were 
founded on a great number of experiments 
carefully performed, which are detailed in 
the October number. In mixing strong 
liquid acid with water, I found that some 
heat is evolved, and a small condensation of 
volume is experienced, contrary to the ob- 
servation of Mr Kirwan. Hence this acid 
forms no longer an exception, as that emi- 
nent chemist taught, to the general law of 
condensation of volume which liquid acids 
obey in their progressive dilutions. Hither- 
to, indeed, many chemists have, without due 
consideration, assumed the half sum or arith- 
metical mean of two specific gravities, to be 
E 



ACID 



66 



MURIATIC. 



the truly computed mean; and on compar- 
ing the number thus obtained with that 
derived from experiment, they have inferred 
the change of volume occasioned by chemical 
combination. The errors into which this false 
mode of computation leads are excessively 
great, when the two bodies differ consider- 
ably in their specific gravities. A view of 
these erroneous results was given in my third 
table of sulphuric acid, published in the 7th 
number of the Journal of Sciences and the 
Arts, and reprinted in this Dictionary, arti- 
cle SPECIFIC GRAVITY. When, however, the 
two specific gravities do not differ much, the 
errors become less remarkable. It is a 
singular fact, that the arithmetical mean, 
which is always greater than the rightly com- 
puted mean specific gravity, gives, in the case 
of liquid muriatic acid, an error in excess, 
very nearly equal to the actual increase of 
density. The curious coincidence thus acci- 
dentally produced between accurate experi- 



ments and a false mode of calculation, i^ 
very instructive, and ought to lead chemists 
to verify every anomalous phenomenon by 
independent modes of research. Had Mr 
Kirwan, for example, put into a nicely gra- 
duated tube 50 measures of strong muriatic 
acid, and poured gently over it 50 measures 
of water, he would have found, after agita- 
tion, and cooling the mixture to its former 
temperature, that there was a decided dimi- 
nution of volume, as I experimentally ascer- 
tained. 

Having had occasion more lately to sub- 
ject muriatic acid, in different states of dilu- 
tion, to a very rigorous examination, I per- 
ceived small deviations in the new results 
from my former tabular quantities, which in- 
duced me to revise the whole with the great- 
est possible care, both in experiment and 
calculation. The following Table I believe 
to approach very near to the truth. 



TABLE OF MURIA TIC A CID, by DB UKE. 



Acid 
of 1.20 
in 100. 


Specific 
gravity. 


Chlo- 
rine. 


Muriatic 
Gas. 


Acid 

of 1.20 
in 100. 


Specific 
gravity. 


Chlo- 
rine. 


Muriatic 
Gas. 


Acid 
of 1.20 
in 100. 


Specific 
gravity. 


Chlo- 
rine. 


Muriatic 
Gas. 


100 


.2000 


39.675 


40.777 


66 


1.1328 


26.186 


26.913 


32 


.0637 


12.697 


13.049 


99 


.1982 


39.278 


40.369 


65 


1.1308 


25.789 


26.505 


31 


.0617 


12.300 


12.641 


98 


.1964 


38.882 


39.961 


64 


1.1287 


25.392 


26.098 


30 


.0597 


11.903 


12.233 


97 


.1946 


38.485 


39.554 


63 


.1267 


24.996 


25.690 


29 


.0577 


11.506 


11.825 


96 


.1928 


38.089 


39.146 


62 


.1247 


24.599 


25.282 


28 


.0557 


11.109 


11.418 


95 


.1910 


37.692 


38.738 


61 


.1226 


24.202 


24.874 


27 


.0537 


10.712 


11.010 


94 


.1893 


37.296 


38.330 


60 


.1206 


23.805 


24.466 


26 


.0517 


10.316 


10.602 


93 


.1875 


36.900 


37.923 


59 


.1185 


23.408 


24.058 


25 


.0497 


9.919 


10.194 


92 


.1857 


36.503 


37.516 


58 


.1164 


23.012 


23.650 


24 


.0477 


9.522 


9.786 


91 


.1846 


36.107 


37.108 


57 


.1143 


22.615 


23.242 


23 


.0457 


9.126 


9.379 


90 


.1822 


35.707 


36.700 


56 


.1123 


22.218 


22.834 


22 


.0437 


8.729 


8.971 


89 


.1802 


35.310 


36.292 


55 


.1102 


21.822 


22.426 


21 


.0417 


8.332 


8.563 


88 


.1782 


34.913 


35.884 


54 


.1082 


21.425 


22.019 


20 


.0397 


7.935 


8.155 


87 


.1762 


34.517 


35.476 


53 


.1061 


21.028 


21.611 


19 


.0377 


7.538 


7.747 


86 


.1741 


34.121 


35.068 


52 


.1041 


20.632 


21.203 


18 


.0357 


7.141 


7.340 


85 


.1721 


33.724 


34.660 


51 


.1020 


20.235 


20.796 


17 


.0337 


6.745 


6.932 


84- 


.1701 


33.328 


34.252 


50 


.1000 


19.837 


20.388 


16 


.0318 


6.348 


6.524 


83 


.1681 


32.931 


33.845 


49 


.0980 


19.440 


19.980 


15 


.0298 


5.951 


6.116 


82 


.1661 


32.535 


33.437 


48 


.0960 


19.044 


19.572 


14 


.0279 


5.554 


5.709 


81 


.1641 


32. 136 


33.029 


47 


.0939 


18.647 


19.165 


13 


.0259 


5.158 


5.301 


80 


.1620 


31.746 


32.621 


46 


.0919 


18.250 


18.757 


12 


.0239 


4.762 


4.893 


79 


.1599 


31.343 


32.213 


45 


.0899 


17.854 


18.349 


11 


.0220 


4.365 


4.486 


78 


.1578 


30.946 


31.805 


44 


.0879 


17.457 


17.941 


10 


.0200 


3.968 


4.078 


77 


.1557 


30.550 


31.398 


43 


.0859 


17.060 


17.534 


9 


.0180 


3.571 


3.670 


76 


.1536 


30.153 


30.990 


42 


.0838 


16.664 


17.126 


8 


.0160 


3.174 


3.262 


75 


.1515 


29.757 


30.582 


41 


.0818 


16.267 


16.718 


7 


.0140 


2.778 


2.854 


74 


.1494 


29.361 


30.174 


40 


.0798 


la.870 


16.310 


6 


.0120 


2.381 


2.447 


73 


.1473 


28.964 


29.767 


39 


.0778 


15.474 


15.902 


5 


.0100 


1.984 


2.039 


72 


.1452 


28.567 


29.359 


38 


.0758 


15.077 


15.494 


4 


.0080 


1.588 


1.631 


71 


.1431 


28.171 


28.951 


37 


.0738 


14.680 


15.087 


3 


.0060 


1.191 


1.2*4 


70 


.1410 


27.772 


28.544 


36 


.0718 


14.284 


14.679 


2 


.0040 


0.795 


0.816 


69 


. 1389 


27.376 


28.136 


35 


.0697 


13.887 


14.271 


1 


.0020 


0.397 


0.408 


68 


.1369 


26.979 


27.728 


34 


.0677 


13.490 


13.863 










67 


.1349 


26.583 


27.321 


33 


1.0657 


13.094 


13.456 











ACID 



67 



MURIATIC. 



At the density 1.199, Mr Dalton's table* 
has 25.6 per cent of real muriatic acid by 
weight, equivalent to only 32.9 chlorine, in- 
stead of 39.47, which I believe to be the ex- 
act value. If we term the correct quantity 
JOO, then Mr Dalton's number would be 
only 83; which is no less than 17 per cent 
of defect from the truth. I have purposely 
omitted in this new table the column of dry, 
or, as it was also called, real muriatic acid ; 
first, because there is no evidence at present 
of the existence of any such body ; and se- 
condly, because, though it was a convenient 
column for finding by inspection the increase 
of weight which any salifiable base would ac- 
quire by saturation with the liquid acid, yet 
that convenience may be obtained by the fol- 
lowing simple calculation. Since the prime 
equivalent of chlorine is to that of the sup- 
posed dry muriatic acid in the ratio of 45 to 
35, or 9 to 7; if we multiply the number 
opposite to the given specific gravity, in the 
chlorine column, by 9, and divide by 7, we 
shall have the relative quantity ofthefixable 
muriatic acid Journ. of Science, xii. 267. 

From the curious coincidence above no- 
ticed, we derive a very simple rule for find- 
ing the approximate value of chlorine in the 
liquid acid at any density. Multiply the 
decimal part of the number representing the 
specific gravity by 200, the product will be 
the chlorine present in 100 parts. Thus, 
the specific gravity is 1.0437, what is the 
quantity per cent of chlorine? 0.0437 X 
200=8.74. Now the tabular number is 
8.729. The sp. gravity being 1.059, what 
is the value of the chlorine in 100 parts? 
0.059 X 200 = 1 1.8. The table has 11.9. 
Towards the head of the table this rule gives 
a slight error in excess, and towards the 
foot an equally slight error in defect ; but the 
approximation is always good enough for 
ordinary practice, seldom amounting to one- 
half per cent. If to the number thus found 
for chlorine we add ^ part, the sum is the 
corresponding weight of muriatic acid gas. 

We have seen it stated, that water, in ab- 
sorbing 480 times its bulk of the acid gas, 
becomes of specific gravity 1.2109. If we 
compute from these data the increase of its 
bulk, we shall find it equal to 1.42, or nearly 
one and a half of the volume of the water. 
481 parts occupy only 1.42 in bulk, a con- 
densation of about 340 into one. The con- 
sequence of this approximation of the parti- 
cles is the evolution of their latent heat ; and 
accordingly the heat produced in the conden- 
sation of the gas is so great, that it melts ice 
almost as rapidly as the steam of boiling 
water does. Hence also, in passing the gas 
from the beak of a retort into a Woolfe's ap- 
paratus containing water to be impregnated, 
it is necessary to surround the bottles with 

* New System of Chemical Philosophy, p.g95. 



cold water or ice, if we wish a considerable 
condensation. 

By uniting the base of this gas with silver, 
and also with potassium, Berzelius determin- 
ed the prime equivalent of muriatic acid to 
be 3.426 1 , whence chlorine comes out 4. 426 1, 
and muriatic gas 4.4261 -{- 0. 125 (the prime 
of hydrogen) = 4. 55 11. But if we take 
1.2847 as the specific gravity of this acid gas, 
then the specific gravity of chlorine will be 
twice that number, minus the specific gravity 
of hydrogen, or (1.2847 X 2) 0.0694 = 
2.5; and as chlorine and hydrogen unite 
volume to volume, then the relation of the 
prime of chlorine will be to that of hydrogen 

a 5 
= -^- = 36. If we divide this by 8, 



we shall have 4.5 to represent the prime 
equivalent of chlorine, and 4.5 -f- 0.125 = 
4.625, for that of muriatic acid gas. 

Muriatic acid, from its composition, has 
been termed by M. Gay Lussac the hydro- 
chloric acid ; a name objected to on good 
grounds by Sir H. Davy. It was prepared 
by the older chemists in a very rude manner, 
and was called by them Spirit of Salt. 

Muriatic was anciently extracted from com- 
mon salt, by igniting a mixture of it and soft 
clay kneaded up together. 

Sir H. Davy first gave the just explana- 
tion of this decomposition. Common salt is 
a compound of sodium and chlorine. The 
sodium may be conceived to combine with 
the oxygen of the water in the earth, and with 
the earth itself, to form a vitreous compound ; 
and the chlorine to unite with the hydrogen 
of the water, forming muriatic acid gas. " It 
is also easy," adds he, " according to these 
new ideas, to explain the decomposition of 
salt by moistened litharge, the theory of 
whiclThas so much perplexed the most acute 
chemists. It may be conceived to be an in- 
stance of compound affinity : the chlorine is 
attracted by the lead, and the sodium com- 
bines with the oxygen of the litharge, and 
with water, to form hydrate of soda, which 
gradually attracts carbonic acid from the air. 
When common salt is decomposed by oil of 
vitriol, it was usual to explain the phenome- 
non by saying, that the acid, by its superior 
affinity, aided by heat, expelled the gas, and 
united to the soda. But as neither muriatic 
acid nor soda exists in common salt, we must 
now modify the explanation by saying, that 
the water of the oil of vitriol is first decom- 
posed ; its oxygen unites to the sodium to 
form soda, which is seized on by the sulphu- 
ric acid ; while the chlorine combines with 
the hydrogen of the water, and exhales in the 
form of muriatic acid gas." 

As 100 parts of dry sea salt are capable of 
yielding 62 parts by weight of muriatic acid 
gas, these ought to afford, by economical 
management, nearly 221 parts of liquid acid, 
specific gravity 1.142, as prescribed by the 



ACID 



MURIATIC. 



London College, or 200 parts of acid, sp. gr. 
1.160, as directed by the Edinburgh and 
Dublin Pharmacopoeias. 

The fluid ounce of the London College be- 
ing 1 16th of a wine pint, is equal in weight 
to 1.26581 7 Ibs. Troy, divided by 16, which 
gives 453.7 grains Troy. This weight mul- 
tiplied by 1.142, = the specific gravity of 
their standard acid, gives the product 520.4 ; 
which being multiplied by 0.2874, the mu- 
riatic gas in 1.00 by my table, we have 
149.56 for the acid gas in the liquid ounce 
of the above density. We find this quantity 
equivalent to 203 gr. of carbonate of lime. 
When this acid is contaminated with sulphu- 
ric acid, it affords precipitates with muriates 
of baryta and strontia. 

The English manufacturers use iron stills 
for this distillation, with earthen heads. 

The muriates, when in a state of dryness, 
are actually chlorides, consisting of chlorine 
and the metal ; yet they may be conveniently 
treated of under the title muriates. 

Muriate of baryta crystallizes in tables 
bevelled at the edges, or in octaedral pyra- 
mids applied base to base. It is soluble in 
five parts of water at 60, in still less at a 
boiling heat, and also in alcohol. It is not 
altered in the air, and but partly decompos- 
able by heat. The sulphuric acid separates 
its base; and the alkaline carbonates and 
sulphates decompose it by double affinity. It 
is best prepared by dissolving the carbonate 
in dilute muriatic acid; and if contaminated 
with iron or lead, which occasionally happens, 
these may be separated by the addition of 
a small quantity of liquid ammonia, or by 
boiling and stirring the solution with a little 
baryta. M. Goettling recommends to pre- 
pare it from the sulphate of baryta; eight 
parts of which in fine powder are to be mixed 
with two of muriate of soda, and one of 
charcoal powder. This is to be pressed hard 
into a Hessian crucible, and exposed for an 
hour and a half to a red heat in a wind fur- 
nace. The cold mass, being powdered, is to 
be boiled a minute or two in sixteen parts of 
water, and then filtered. To this liquor 
muriatic acid is to be added by little and 
little, till sulphuretted hydrogen ceases to be 
evolved ; it is then to be filtered, a little hot 
water to be poured on the residuum, the liquor 
evaporated to a pellicle, filtered again, and 
then set to crystalli/e. As the muriate of 
soda is much more soluble than the muriate 
of baryta, and does not separate by cooling, 
the muriate of baryta will crystallize into a 
perfectly white salt, and leave the muriate of 
soda in the mother water, which may be 
evaporated repeatedly till no more muri- 
ate of baryta is obtained. This salt was 
first employed in medicine by Dr Crawford, 
t-hiefly in scrofulous complaints and cancer, 
beginning with doses of a few drops of the 
saturated solution twice a-dav, and increas- 



ing it gradually, as far as forty or fifty drops 
in some instances. In large doses it excites 
nausea, and has deleterious effects. As a 
test of sulphuric acid, it is of great use. 

Mr Phillips states the composition of the 
crystals to be I atom chloride of barium -}- 2 
atoms water. 

Muriate of potash, formerly known by the 
names of Febrifuge salt of Sylvius, crystallizes 
in regular cubes, or in rectangular parallelo- 
pipedons ; decrepitating on the fire. Their 
taste is saline and bitter. They are soluble 
in thrice their weight of cold water, and in 
but little less of boiling water, so as to re- 
quire spontaneous evaporation for crystalliz- 
ing. Fourcroy recommends to cover the 
vessel with gauze, and suspend hairs in it, 
for the purpose of obtaining regular crystals. 

It is sometimes prepared in decomposing 
sea salt by common potash for the purpose 
of obtaining soda; and maybe formed by 
the direct combination of its constituent 
parts. 

Muriate of soda, or common salt, is of 
considerable use in the arts, as well as a 
necessary ingredient in our food. It crys- 
tallizes in cubes, which are sometimes group- 
ed together in various ways, and not unfre- 
quently form hollow quadrangular pyramids. 
In the fire it decrepitates, melts, and is at 
length volatilized. When pure it is net de- 
liquescent. One part is soluble in 2 of 
cold >vater, and in little less of hot, so that 
it cannot be crystallized but by evaporation. 

Common salt is found in large masses, or 
in rocks under the earth, in England and 
elsewhere. In the solid form it is called sal 
gem, or rock salt. This rock salt is never 
used on our tables in its crude state, as the 
Polish rock salt is. 

The waters of the ocean everywhere abound 
with common salt, though in different pro- 
portions. The water of the Baltic Sea is 
said to contain one sixty-fourth of its weight 
of salt ; that of the sea between England and 
Flanders contains one thirty-second part ; 
and that on the coast of Spain one sixteenth 
part. 

The whole art of extracting salt from 
waters which contain it, consists in evaporat- 
ing the water in the cheapest and most con- 
venient manner. 

There is no difference between this salt 
and the lake salt extracted from different 
lakes, excepting such as may be occasioned 
by the casual intervention of some substances. 

At several places in Germany, and at Mont- 
marot in France, the waters of salt springs 
are pumped up to a large reservoir at the 
top of a building or shed ; from which it 
drops or trickles through small apertures up- 
on boards covered with brushwood. -The 
large surface of the water thus exposed to 
the air causes a very considerable evapora- 
tion ; and the brine is afterward conveyed to 



ACID 



MURIATIC. 



the boilers, for the perfect separation of the 
salt. 

To free common salt from those mixtures 
that render it deliquescent, and less fit for 
the purposes to which it is applied, it may 
be put into a conical vessel with a small aper- 
ture at the point, and a saturated solution of 
the muriate of soda boiling hot be poured on 
it. This solution will dissolve and carry off 
any other salts mixed with the soda, and 
leave it quite pure, by repeating the process 
three or four times. 

At present, the greater part of the carbo- 
nate of soda in the market is furnished by 
decomposing the sulphate of soda left, after 
the chlorine is expelled in the usual way of 
eliminating it from common salt. Mix the 
sulphate of soda with an equal weight of 
chalk, and rather more than half its weight 
of charcoal powder, and expose the mixture 
in a reverberatory furnace to a heat sufficient 
to bring them to a state of imperfect lique- 
faction. Much of the sulphur formed will 
be expelled in vapour and burned, the mix- 
ture being frequently stirred to promote this ; 
and this is continued till the mass on cooling 
assumes a fine grain. It is then left exposed 
to a humid atmosphere, and the carbonate of 
soda may be extracted by lixiviation, the sul- 
phur not consumed having united with the 
lime. 

Beside its use in seasoning our food, and 
preserving meat both for domestic consump- 
tion and during the longest voyages, and in 
furnishing us with the muriatic acid and 
soda, salt forms a glaze for coarse pottery, 
by being thrown into the oven where *it is 
baked ; it improves the whiteness and clear- 
ness of glass ; it gives hardness to soap ; in 
melting metals it preserves their surface from 
calcination, by defending them from the air, 
and is employed with advantage in some 
assays ; it is used as a mordant, and for im- 
proving certain colours, and enters more or 
less into many other processes of the arts. 

Muriate of strontia crystallizes in very 
slender hexagonal prisms, has a cool pungent 
taste, without the austerity of the muriate of 
baryta, or the bitterness of the muriate of 
lime; is soluble in 0.75 of water at 60, 
and to almost any amount in boiling water ; 
is likewise soluble in alcohol, and gives a 
blood-red colour to its flame. 

It has never been found in nature, but 
may be prepared in the same way as the 
muriate of baryta. 

Muriate of lime crystallizes in hexaedral 
prisms terminated by acute pyramids; but 
if the solution be greatly concentrated, and 
exposed to a low temperature, it is condensed 
in confused bundles of needley crystals. Its 
taste is acrid, bitter, and very disagreeable. 
It is soluble in half its weight of cold water, 
and by heat in its own water of crystalliza- 
tion. It is one of the most deliquescent 



salts known ; and when deliquesced has been 
called oil of lime. It exists in nature, but 
neither very abundantly nor very pure. It 
is formed in chemical laboratories, in the 
decomposition of muriate of ammonia ; and 
Homberg found, that if it were urged by a 
violent heat till it condensed, on cooling, into 
a vitreous mass, it emitted a phosphoric light 
upon being struck by any hard body; in 
which state it was called JHombery's Phos- 
phorus. 

Muriate of ammonia has long been known 
by the name of sal ammonia or ammoniac. 
It is found native in the neighbourhood of 
volcanoes, where it is sublimed sometimes 
nearly pure, and in different parts of Asia 
and Africa. A great deal is carried annual- 
ly to Russia and Siberia from Bucharian 
Tartary ; and we formerly imported large 
quantities from Egypt, but now manufacture 
it at home. See AMMONIA. 

This salt is usually in the form of cakes, 
with a convex surface on one side, and con- 
cave on the other, from being sublimed into 
large globular vessels ; but by solution it may 
be obtained in regular quadrangular crystals. 
It is remarkable for possessing a certain de- 
gree of ductility, so that it is not easily pul- 
verable. It is soluble in 3^ parts of water 
at 60, and in little more than its own weight 
of boiling water. Its taste is cool, acrid, and 
bitterish. Its specific gravity is 1.42. It at- 
tracts moisture from the air, but very slightly. 

In tinning and soldering, it is employed 
to preserve the surface of the metals from 
oxidation. In assaying, it discovers iron, 
and separates it from some of its combina- 
tions. 

Muriate of magnesia is extremely deliques- 
cent, soluble in an equal weight of water, 
and difficultly crystallizable. It dissolves 
also in five parts of alcohol. It is decom- 
posable by heat, which expels its acid. Its 
taste is intensely bitter. 

With ammonia this muriate forms a triple 
salt, crystallizable in little polyedrons, which 
separate quickly from the water, but are not 
very regularly formed. Its taste partakes of 
that of both the preceding salts. The best 
nnode of preparing it is by mixing a solution 
of 27 parts of muriate of ammonia with a 
solution of 73 of muriate of magnesia; but 
it may be formed by a semi-decomposition of 
either of these muriates by the base of the 
other. It is decomposable by heat, and re- 
quires six or seven times its weight of water 
to dissolve it. 

Muriate of glucina appears to crystallize 
in very small crystals ; to be decomposable 
by heat ; and, dissolved in alcohol and diluted 
with water, to form a pleasant saccharine 
liquor. 

Muriate of alumina is scarcely crystalliz- 
able, as on evaporation it assumes the state 
of a thick jelly. It has an acid, styptic, acrid 



ACID 



70 



CHLORIC. 



taste. It is extremely soluble in water, and 
deliquescent. Fire decomposes it. It may 
be prepared by directly combining the muri- 
atic acid with alumina, but the acid always 
remains in excess. 

Muriate of zirconia crystallizes in small 
needles, which are very soluble, attract mois- 
ture, and lose their transparency in the air. 
It has an austere taste, with somewhat of 
acrimony. It is decomposable by heat. The 
gallic acid precipitates from its solution, if it 
be free from iron, a white powder. Carbo- 
nate of ammonia, if added in excess, redis- 
solves the precipitate it had before thrown 
down. 

Muriate of yttria does not crystallize when 
evaporated, but forms a jelly; it dries with 
difficulty, and deliquesces. See SALT. 

ACID (MURIATIC, OXYGENAT- 
ED). See CHLORINE. 

ACID (MURIATIC, OXYGENIZ- 
ED.) Th is supposed acid was lately descri b- 
ed by M. Thenard. He saturated common 
muriatic acid of moderate strength with deut- 
oxide of barium, reduced into a soft paste by 
trituration with water. He then precipi- 
tated the baryta from the liquid, by adding 
the requisite quantity of sulphuric acid. He 
next took this oxygenized muriatic acid, and 
treated it with deutoxide of barium and sul- 
phuric acid, to oxygenate it anew. In this 
way he charged it with oxygen as often as 15 
times. He thus obtained a liquid acid, which 
contained 32 times its volume of oxygen at 
the temperature of 68 Fahr. and at the or- 
dinary atmospherical pressure, and only 4^ 
times its volume of muriatic acid, which gives 
about 28 equivalent primes of oxygen to 1 
of muriatic acid. For the ratio of oxygen 
to the acid, by weight, is 1 to 4.6 ; but by 
measure the ratio will be as these two num- 
bers respectively divided by the specific gra- 
vity of the gases, or as j to ^ 
which by reduction makes nearly one volume 
of oxygen, equivalent to four of muriatic acid. 
Now, the oxygen in the above result, instead 
of being l-4th of the volume of the acid gas, 
was seven times greater, whence we derive 
the number 28. Still more oxygen may 
however be added. On putting the above 
oxygenized acid in contact with sulphate of 
silver, an insoluble chloride of this metal sub- 
sides, and the liquid is oxygenized sulphuric 
acid. When this is passed through the filter, 
muriatic acid is added to it, but in smaller 
quantity than existed in the original oxygen- 
ized acid. A quantity of baryta, just suffi- 
cient to precipitate the sulphuric acid, is then 
added. Instantly the oxygen, leaving the 
sulphuric acid to unite with the muriatic acid, 
brings that acid to the highest point of oxy- 
genation. Thus we see that we can transfer 
the whole of the oxygen from one of these 
acids to the other : and on a little reflection 
it will be evident, that to obtain sulphuric 



acid in the highest degree of oxygenation, it 
will be merely necessary to pour baryta water 
into oxygenated sulphuric acid, so as to pre- 
cipitate only a part of the acid. 

All these operations, with a little practice, 
may be performed without the least difficulty. 
By combining the two methods just describ- 
ed, M. Thenard found that he could obtain 
oxygenized muriatic acid, containing nearly 
16 times as many volumes of oxygen as of 
muriatic acid ; which represents about 64 
equivalent primes of the former to 1 of the 
latter. This oxygenized acid leaves no resi- 
duum when evaporated. It is a very acid 
colourless liquid, almost destitute of smell, 
and powerfully reddens turnsole. When 
boiled for some time, its oxygen is expelled. 
It dissolves zinc without effervescence. Its 
action on the oxide of silver is curious. These 
two bodies occasion as lively an effervescence 
as if an acid were poured upon a carbonate. 
Water and a chloride are formed, while the 
oxygen is evolved. This oxide enables us to 
determine the quantity of oxygen present in 
the oxygenized acid. Pour mercury into a 
graduated glass tube, leaving a small deter- 
minate space, which must be filled with the 
above acid, invert the tube in mercury, let 
up oxide of silver diffused in water ; instantly 
the oxygen is separated. 

We ought, however, to regard this appa- 
rent oxygenation of the acid, merely as the 
conversion of a portion of its combined water 
into deutoxide of hydrogen. The same ex- 
planation may be extended to the other oxy- 
genized acids of M. Thenard. See WATEE. 

ACID (CHLORIC). We place this acid 
after the muriatic acid, because it has chlo- 
rine also for its base. It was first eliminat- 
ed from the salts containing it by M. Gay 
Lussac, and described by him in his admira- 
ble memoir on iodine, published in the 91st 
volume of the Annales de Chimie. When a 
current of chlorine is passed for some time 
through a solution of barytic earth in warm 
water, a substance called hyperoxymuriate of 
baryta by its first discoverer, M. Chenevix, 
is formed, as well as some common muriate. 
The latter is separated, by boiling phosphate 
of silver in the compound solution. The 
former may then be obtained by evaporation, 
in fine rhomboidal prisms. Into a dilute 
solution of this salt M. Gay Lussac poured 
weak sulphuric acid. Though he added 
only a few drops of acid, not nearly enough 
to saturate the baryta, the liquid became sen- 
sibly acid, and not a bubble of oxygen escap- 
ed. By continuing to add sulphuric acid with 
caution, he succeeded in obtaining an acid 
liquid entirely free from sulphuric acid and 
baryta, and not precipitating nitrate of silver. 
It was chloric acid dissolved in water. Its 
characters are the following: 

This acid has no sensible smell. Its so- 
lution in water is perfectly colourless. Its 



ACID 



71 



CHLORIC. 



taste is very acid, and it reddens litmus with- 
out destroying the colour. It produces no 
alteration on solution of indigo in sulphuric 
acid. Light does not decompose it. It may 
be concentrated by a gentle heat, without un- 
dergoing decomposition, or without evapora- 
ting. It was kept a long time exposed to 
the air without sensible diminution of its 
quantity. When concentrated, it has some- 
thing of an oily consistency. When exposed 
to heat, it is partly decomposed into oxygen 
and chlorine, and partly volatilized without 
alteration. Muriatic acid decomposes it in 
the same way, at the common temperature. 
Sulphurous acid, and sulphuretted hydrogen, 
have the same property ; but nitric acid pro- 
duces no change upon it. Combined with 
ammonia, it forms a fulminating salt, former- 
ly described by M. Chenevix. It does not 
precipitate any metallic solution. It readily 
dissolves zinc, disengaging hydrogen ; but it 
acts slowly on mercury. It cannot be ob- 
tained in the gaseous state. It is compos- 
ed of 1 volume chlorine -j- 2.5 oxygen, or 
by weight, of 100 chlorine -f- 111.70 oxy- 
gen, if we consider the specific gravity of 
chlorine to be 2.4866. But if it be called 
2.420, as M. Gay Lussac does in his memoir, 
it will then come out 100 chlorine -|- 114.7 
oxygen. This last number is however too 
great, in consequence of estimating the spe- 
cific gravity of oxygen 1.1111, while M. Gay 
Lussac makes it 1.10359. Chloric acid is 
at any rate a compound of 5 primes of oxy- 
gen -J- 1 of chlorine =5-4- 4.5. 

M. Vauquelin, in making phosphate of 
silver act on the mixed saline solution above 
described, tried to accelerate its action by dis- 
solving it previously in acetic acid. But on 
evaporating the chlorate of baryta so obtained 
to dryness, and exposing about 30 grains to 
a decomposing heat, a tremendous explosion 
took place, which broke the furnace, rent a 
thick platina crucible, and drove its lid into 
the chimney, where it stuck. It was the em- 
ployment of acetic acid which occasioned 
this accident, and therefore it ought never to 
be used in this way. 

To the preceding account of the properties 
of chloric acid, M. Vauquelin has added the 
following : Its taste is not only acid but 
astringent, and its odour, when concentrated, 
is somewhat pungent. It differs from chlo- 
rine, in not precipitating gelatin. When 
paper stained with litmus is left for some time 
in contact with it, the colour is destroyed. 
Mixed with muriatic acid, water is formed, 
and both acids are converted into chlorine. 
Sulphurous acid is converted into sulphuric, 
by taking oxygen from the chloric acid, which 
is consequently converted into chlorine. 

Chloric acid combines with the bases, and 
forms the chlorates, a set of salts formerly 
known by the name of the hyperoxygenized 
muriates. They may be formed either di- 



rectly by saturating the alkali or earth with 
the chloric acid, or by the old process of 
transmitting chlorine through the solutions 
of the bases in Woolfe's bottles. In this 
case the water is decomposed. Its oxygen 
unites to one portion of the chlorine, form- 
ing chloric acid, while its hydrogen unites to 
another portion of chlorine, forming muriatic 
acid ; and hence, chlorates and muriates must 
be contemporaneously generated, and must be 
afterwards separated by crystallization, or pe- 
culiar methods. 

The chlorate of potash or hyperoxymuriate 
has been long known. When exposed to a 
red heat, 100 grains of this salt yield 38.88 
of oxygen, and are converted into the chloride 
of potassium, or the dry muriate. This re- 
mainder of 61.12 grains consists of 32.19 
potassium and 28.93 chlorine. But 32. 19 
potassium require 6.50 oxygen, to form the 
potash which existed in the original chlo- 
rate. Therefore, subtracting this quantity 
from 38.88, we have 32.38 for the oxygen 
combined with the chlorine, constituting 
61.31 of chloric acid, to 38.69 of potash. 

Chlorate of potash may be procured by 
receiving chlorine, as it is formed, into a so- 
lution of potash. When the solution is sa- 
turated, it may be evaporated gently, and the 
first crystals produced will be the salt desired ; 
this crystallizing before the simple muriate, 
which is produced at the same time with it. 
Its crystals are in shining hexaedral lamina?, 
or rhornboidal plates. 

Its taste is cooling, and rather unpleasant. 
Its specific gravity is 2.0. Sixteen parts of 
water, at 60, dissolve one of it, and 2|- of 
boiling water. The purest oxygen is extract- 
ed from this salt, by exposing it to a gentle 
red heat. One hundred grains yield about 
1 15 cubic inches of gas. It consits of 9.5 
chloric acid -f- 6 potash = 15.5, which is 
the prime equivalent of the salt. It is inca- 
pable of discharging vegetable colours ; but 
the addition of a little sulphuric acid deve- 
lopes this prcperty. So likewise a few grains 
of it, added to muriatic acid, give it this pro- 
perty. 

The effects of this salt on inflammable 
bodies are very powerful. Rub two grains 
into powder in a mortar, add a grain of sul- 
phur, mix them well by gentle trituration, 
then collect the powder into a heap, and press 
upon it suddenly and forcibly with the pestle, 
a loud detonation will ensue. If the mixture 
be wrapped in strong paper, and struck with 
a hammer, the report will be still louder. 
Five grains of the salt, mixed in the same 
manner with two and a half of charcoal, will 
be inflamed by strong trituration, especially if 
a grain or two of sulphur be added, but with- 
out much noise. If a little sugar be mixed 
with half its weight of the chlorate, and a 
little strong sulphuric acid poured on it, a 
sudden and vehement inflammation will en- 



ACID 



72 



PERCHLORIC. 



sue ; but this experiment requires caution, as 
well as the following. To one grain of the 
powdered salt in a mortar, add half a grain of 
phosphorus ; it will detonate with a loud 
report, on the gentlest trituration. In this 
experiment the hand should be defended by 
a glove, and great care should be taken that 
none of the phosphorus get into the eyes. 
Phosphorus may be inflamed by it under 
water, putting into a wine glass one part of 
phosphorus and two of the chlorate, nearly 
filling the glass with water, and then pouring 
in, through a glass tube reaching to the bot- 
tom, three or four parts of sulphuric acid. 
This experiment, too, is very hazardous to the 
eyes. If olive or linseed oil be taken instead 
of phosphorus, it may be inflamed by similar 
means on the surface of the water. This salt 
should not be kept mixed with sulphur, or 
perhaps any inflammable substance, as in 
this state it has been known to detonate 
spontaneously. 

Chlorate of soda may be prepared in the 
same manner as the preceding, by substitut- 
ing soda for potash ; but it is not easy to 
obtain it separate, as it is nearly as soluble 
as the muriate of soda, requiring only three 
parts of cold water. Vauquelin formed it 
by saturating chloric acid with soda ; 500 
parts of the dry carbonate yielding 1100 
parts of crystallized chlorate. It consists of 
4 soda -f- 9.5 acid = 13.5, which is its 
prime equivalent. It crystallizes in square 
plates, produces a sensation of cold in the 
mouth, and a saline taste ; is slightly deli- 
quescent, and in its other properties resembles 
the chlorate of potash. 

Baryta appears to be the next base in order 
of affinity for this acid. The best method of 
forming it, is to pour hot water on a large 
quantity of this earth, and to pass a current 
of chlorine through the liquid kept warm, so 
that a fresh portion of baryta may be taken 
up as the former is saturated. This salt is 
soluble in about four parts of cold water, 
and less of warm, and crystallizes like the 
simple muriate. It may be obtained, how- 
ever, by the agency of double affinity; for 
phosphate of silver boiled in the solution will 
decompose the simple muriate, and the mu- 
riate of silver and phosphate of baryta being 
insoluble, will both fall down and leave the 
chlorate in solution alone. The phosphate 
of silver employed in this process must be 
perfectly pure, and not the least contaminat- 
ed with copper. 

The chlorate of strontia may be obtained 
in the same manner. It is deliquescent, 
melts immediately in the mouth, and pro- 
duces cold ; is more soluble in alcohol than 
the simple muriate, and crystallizes in needles. 

The chlorate of lime, obtained in a similar 
way, is extremely deliquescent, liquefies at a 
Jow heat, is very soluble in alcohol, produces 



much cold in solution, and has a sharp bitter 
taste. 

Chlorate of ammonia is formed by double 
affinity, the carbonate of ammonia decompos- 
ing the earthy salts of this genus, giving up 
its carbonic acid to their base, and combin- 
ing with their acid into chlorate of ammonia, 
which may be obtained by evaporation. It 
is very soluble both in water and alcohol, and 
decomposed by a moderate heat. 

The chlorate of magnesia much resembles 
that of lime. 

To obtain chlorate of alumina, M. Chene- 
vix put some alumina, precipitated from the 
muriate, and well washed, but still moist, 
into a Woolfe's apparatus, and treated it as 
the other earths. The alumina shortly dis- 
appeared ; and on pouring sulphuric acid 
into the liquor, a strong smell of chloric 
acid was perceivable ; but on attempting to 
obtain the salt pure by means of phosphate 
of silver, the whole was decomposed, and 
nothing but chlorate of silver was found in 
the solution. M. Chenevix adds, however, 
that the aluminous salt appears to be very 
deliquescent, and soluble in alcohol. See 
SALT. 

ACID (PERCHLORIC). If about 3 
parts of sulphuric acid be poured on 1 of 
chlorate of potash in a retort, and, after the 
first violent action is over, heat be gradually 
applied to separate the deutoxide of chlorine, 
a saline mass will remain, consisting of bi- 
sulphate of potash and perchlorate of potash. 
By one or two crystallizations, the latter salt 
may be separated from the former. It is a 
neutral salt, with a taste somewhat similar to 
the common muriate of potash. It is very 
sparingly soluble in cold water, since at 60 
only Jg is dissolved ; but in boiling water it 
is more soluble. Its crystals are elongated 
octahedrons. It detonates feebly when tri- 
turated with sulphur in a mortar. At the 
heat of 412 it is resolved into oxygen and 
muriate of potash, in the proportion of 46 of 
the former to 54 of the latter. Sulphuric 
acid at 280 disengages the perchloric acid. 
For these facts science is indebted to Count 
Von Stadion. It seems to consist of 7 primes 
of oxygen, combined with 1 of chlorine, or 7.0 
-f- 4.5. These curious discoveries have been 
lately verified by Sir H. Davy. The other 
perchlorates are not known. 

Before leaving the acids of chlorine, we 
shall describe the ingenious method employ- 
ed by Mr Wheeler to procure chloric acid 
from the chlorate of potash. He mixed a 
warm solution of this salt with one of fluo- 
silicic acid. He kept the mixture moderately 
hot for a few minutes, and to insure the per- 
fect decomposition of the salt, added a slight 
excess of the acid. Aqueous solution of am- 
monia will show, by the separation of silica, 
whether any of the fluosilicic acid be left after 



ACID 



73 



NITRIC. 



the decomposition of the chlorate. Thus we 
can effect its complete decomposition. The 
mixture becomes turbid, and fluosilicate of 
potash is precipitated abundantly in the form 
of a gelatinous mass. The supernatant li- 
quid will then contain nothing but chloric 
acid, contaminated with a small quantity of 
fluosilicic. This may be removed by the 
cautious addition of a small quantity of so- 
lution of chlorate. Or, after filtration, the 
whole acid may be neutralized by carbonate 
of baryta; and the chlorate of that earth 
being obtained in crystals, is employed to 
procure the acid, as directed by M. Gay 
Lussac. 

ACID(NANCEIC). An acid called by 
M. Braconnot nanceic, in honour of the town 
of Nancy where he lives. He discovered it 
in many acescent vegetable substances; in 
sour rice; in putrefied juice of beet-root ; in 
sour decoction of carrots, pease, &c. He 
imagines that this acid is generated at the 
same time as vinegar in organic substances, 
when they become sour. It is without co- 
lour, does not crystallize, and has a very acid 
taste. 

He concentrates the soured juice of the 
beet-root till it become almost solid, digests 
it with alcohol, and evaporates the alcoholic 
solution to the consistence of syrup. He di- 
lutes this with water, and throws into it car- 
bonate of zinc till it be saturated. He passes 
the liquid through a filter, and evaporates till 
a pellicle appears. The combination of the 
new acid with oxide of zinc crystallizes. 
After a second crystallization, he redissolves 
it in water, pours in an excess of water of 
baryta, decomposes by sulphuric acid the 
barytic salt formed, separates the deposit by 
a filter, and obtains, by evaporation, the new 
acid pure. 

It forms with alumina a salt resembling 
gum, and with magnesia one unalterable in 
the air, in little granular crystals soluble in 
25 parts of water at 66 Fahr. ; with potash 
and soda it forms uncrystallizable salts, deli- 
quescent, and soluble in alcohol ; with lime 
and strontia, soluble granular salts; with 
baryta, an uncrystallizable nondeliquescent 
salt, having the aspect of gum ; with white 
oxide of manganese, a salt which crystallizes 
in tetrahedral prisms, soluble in 12 parts of 
water at 60 ; with oxide of zinc, a salt crys- 
tallizing in square prisms, terminated by sum- 
mits obliquely truncated, soluble in 50 parts 
of water at 66 ; with iron, a salt crystallizing 
in slender four- sided needles, of sparing solu- 
bility, and not changing in the air ; with red 
oxide of iron, a white noncrystallizing salt ; 
with oxide of tin, a salt crystallizing in wedge- 
form octahedrons ; with oxide of lead, an un- 
crystallizable salt, not deliquescent, and re- 
sembling a gum ; with black oxide of mer- 
cury, a very soluble salt, which crystallizes 
in needles. See ACID (PECTic). 



ACID (NITRIC). Three parts of pure 
nitrate of potash, coarsely powdered, are to 
be put into a glass retort, with two of strong 
sulphuric acid. This must be cautiously add- 
ed, taking care to avoid the fumes that arise. 
Join to the retort a tubulated receiver of 
large capacity, with an adopter interposed, 
and lute the junctures with glazier's putty. 
In the tubulure fix a glass tube, terminating 
in another large receiver, in which is a small 
quantity of water ; and, if you wish to collect 
the gaseous products, let a bent glass tube 
from this receiver communicate with a pneu- 
matic trough. Apply heat to the receiver 
by means of a sand bath. The first product 
that passes into the receiver is generally red 
and fuming ; but the appearances gradually 
diminish, till the acid comes over pale, and 
even colourless, if the materials used were 
clean. After this it again becomes more and 
more red and fuming, till the end of the 
operation ; and the whole mingled together 
will be of a yellow or orange colour. 

Empty the receiver, and again replace it. 
Then introduce by a small funnel, very cau- 
tiously, one part of boiling water in a slender 
stream, and continue the distillation. A small 
quantity of a weaker acid will thus be ob- 
tained, which can be kept apart. The first 
will have a specific gravity of about 1.500, if 
the heat has been properly regulated, and if 
the receiver was refrigerated by cold water or 
ice. Acid of that density, amounting to two- 
thirds of the weight of the nitre, may thus be 
procured. But commonly the heat is pushed 
too high, whence more or less of the acid is 
decomposed, and its proportion of water unit- 
ing to the remainder, reduces its strength. 
It is not profitable to use a smaller propor- 
tion of sulphuric acid, when a concentrated 
nitric is required. But when only a dilute 
acid, called in commerce aquafortis, is re- 
quired, then less sulphuric acid will suffice, 
provided a portion of water be added. One 
hundred parts of good nitre, sixty of strong 
sulphuric acid, and twenty of water, form 
economical proportions. 

As this acid still holds in solution more or 
less nitrous gas, it is not in fact pure ; it is 
therefore necessary to put it into a retort, to 
which a receiver is added, the two vessels not 
being luted, and to apply a very gentle heat, 
changing the receiver as soon as it is filled 
with red vapours. The nitrous gas will thus 
be expelled, and the nitric acid will remain 
in the retort as limpid and colourless as wa- 
ter. It should be kept in a bottle secluded 
from the light, otherwise it will lose part of 
its oxygen. 

What remains in the retort is a bisulphate 
of potash. 

As nitric acid, in a fluid state, is always 
mixed with water, different attempts have 
been made to ascertain its strength, or the 
quantity of real acid contained in it. 



ACID 



NITRIC. 



Mr Kirwan gave 68 as the quantity of real 
acid in 100 of the liquid acid of specific gra- 
vity 1.500: Sir H. Davy's determination was 
91; Dr Wollaston's, as inferred from the 
experiments of Mr R. Phillips, 75; and Mr 
Dalton's corrected result from Kirwan's table 
was 68. In this state of discordance I per- 
formed a series of experiments, with the view 
of determining the constitution of liquid ni- 
tric acid, and published an account of them, 
with some new tables, in the fourth and sixth 
volumes of the Journal of Science and the 
Arts. 

From regular prisms of nitre I procured, 
by slow distillation, with concentrated oil of 
vitriol, nitric acid; which by the tests of ni- 
trates of silver and of baryta was found to 
be pure. Only the first portion that came 
over was employed for the experiments. It 
was nearly colourless, and had a specific gra- 
vity of 1.500. A redistilled and colourless 
nitric acid, prepared in London, was also 
used for experiments of verification, in esti- 
mating the quantity of dry acid in liquid acid 
of a known density. 

The above acid of 1.500 being mixed in 
numbered phials, with pure water, in the dif- 
ferent proportions of 95 -f 5, 90 -f- 10, 80 
+ 20, &c. I obtained, after due agitation, 
and an interval of 24 hours, liquids whose 
specific gravities, at 60 Fahrenheit, were de- 
termined by means of an accurate balance, 
with a narrow-necked glass globe of known 
capacity. By considering the series of num- 
bers thus obtained, I discovered the geometri- 
cal law which regulates them. The specific 
gravity of dilute acid, containing ten parts in 
the 100 of that whose density is 1.500, is 
1.054. Taking this number as the root, its 
successive powers will give us the successive 
densities, at the terms of 20, 30, 40, &c. per 
cent. Thus 1.054 2 = 1. 1 1 1, is the specific 
gravity corresponding to 20 of the strong li- 
quid acid + 80 water; 1.0543= 1.171, ' ls 
that for 30 per cent of strong acid ; 1.054* = 
1.234, is the specific gravity at 40 per cent. 
The specific gravities are therefore a series of 
numbers in geometrical progression, corres- 
ponding to the terms of dilution, another series 
in arithmetical progression, exactly as I had 
shown in the 7th number of the Journal of 
Science with regard to sulphuric acid. Hence, 
if one term be given, the whole series may 
be found. On uniting the strong acid with 
water, a considerable condensation of volume 
takes place. The maximum condensation oc- 
curs when 58 of acid are mixed with 42 of 
water. Above this point the curve of con- 
densation has a contrary flexure ; and there- 
fore a small modification must be made on 
the root 1.054, in order to obtain with final 
accuracy, in the higher part of the range, the 
numerical powers which represent the specific 
gravities. The modification is, however, very 
simple. To obtain the number for 50 per 



cent, the root is 1.053; and for each decade 
up to 70, the root must be diminished by 
0.002. Thus, for 60, it will become 1.051, 
and for 70, 1.049. Above this we shall 
obtain a precise correspondence with experi- 
ment, up to 1.500 sp. gravity, if for each 
successive decade we subtract 0.0025 from 
the last diminished root, before raising it to 
the desired power, which represents the per- 
centage of liquid acid. 

It is established by the concurring experi- 
ments of Sir H. Davy and M. Gay Lussac, 
that dry nitric acid is a compound of 2 vo- 
lumes of oxygen combined with one of nitro- 
gen ; of which the weights are 2.5 X !! H 
= 2.777 for the proportion of oxygen, and 
0.9722 for that of nitrogen; and in 100 parts, 
of 73^- of the former -f 26| of the latter. 
But nitrogen combines with several inferior 
proportions of oxygen, which are all multiples 
of its prime equivalent 1.0; and the present 
compound is exactly represented by making 
one prime of nitrogen = 1.75, and five of 
oxygen = 5.0 : whence the acid prime is the 
sum of these two numbers, or 6.75. Now 
this result, deduced from its constituents, co- 
incides perfectly with that derived from the 
quantity in which this acid saturates definite 
quantities of the salifiable bases, potash, soda, 
lime, &c. There can be no doubt, therefore, 
that the prime equivalent of the acid is 6.75 ; 
and as little that it consists of five parts of 
oxygen, and 1.75 of nitrogen. Possessed of 
these data, we may perhaps see some reason 
why the greatest condensation of volume, in 
diluting strong liquid acid, should take place 
with 58 of it, and 42 of water. Since 100 
parts of acid of 1.500 contain, by my ex- 
periments, 79. 7 of dry acid, therefore acid of 
the above dilution will contain 46 dry acid, 
and 54 water ; or, reducing the numbers to 
prime proportions, we have the ratio of 6.75 
to 7. 875, being that of one prime of real acid 
to seven primes of water. But we have seen 
that the real acid prime is made up of one of 
nitrogen associated by chemical affinity with 
five of oxygen. Now imagine a figure, in 
which the central prime of nitrogen is sur- 
rounded by five of oxygen. To the upper 
and under surface of the nitrogen let a prime 
of water be attached, and one also to each of 
the primes of oxygen. We have thus the 
seven primes distributed in the most compact 
and symmetrical manner. By this hypothesis 
we can understand, how the elements of acid 
and water may have such a collocation and 
proportion, as to give the utmost efficacy to 
their reciprocal attractions, whence the maxi- 
mum condensation will result. A striking 
analogy will be found in the dilution of sul- 
phuric acid. 

If on 58 parts by weight of acid of 1.500, 
we pour cautiously 42 of water in a graduated 
measure, of which the whole occupies 100 
divisions, and then mix them intimately, the 



ACID 



75 



NITRIC. 



temperature will rise from 60 to 140 ; and 
after cooling to 60 again, the volume will 
be found only 92.65. No other proportion 
of water and acid causes the evolution of so 
much heat. When 90 parts of the strong 
acid *re united with 10 of water, 100 in vo- 
lume become 97 ; and when 10 parts of the 



same acid are combined with 90 of water, the 
resulting volume is 98. It deserves notice, 
that 80 of acid + 20 water, and 30 of acid 
-j- 70 water, each gives a dilute acid, whose 
degree of condensation is the same ; namely, 
100 measures become 94.8. 



TABLE OF NITRIC ACID, by DR UUE. 



Specific 
Gravity. 


Liq. 
Acid 
in 100. 


Dry acid 
in 160. 


Specific 
Gravity. 


Liq. 
Acid 
in 100, 


Dry acid 
in 100. 


Specific 
Gravity. 


Liq. 
Acid 
in 100. 


Dry acid 
in 100. 


Specific 
Gravity. 


Liq. 
Acid 
in 100. 


Dry acid 
in 100. 


1.5000 


100 


79.700 


1.4189 


75 


59.775 


1.2947 


50 


39.850 


1.1403 


25 


19.925 


1.4980 


99 


78.903 


1.4147 


74 


58.978 


1.2887 


49 


39.053 


1.1345 


24 


19.128 


1.4960 


98 


78.106 


1.4107 


73 


58.181 


1.2826 


48 


38.256 


1.1286 


23 


18.331 


1.4940 


97 


77.309 


1.4065 


72 


57.384 


1.2765 


47 


37.459 


1.1227 


22 


17.534 


1.4910 


96 


76.512 


1.4023 


71 


56.587 


1.2705 


46 


36.662 


1.1168 


21 


16.737 


.4880 


95 


75.715 


1.3978 


70 


55.790 


1.2644 


45 


35.865 


1.1109 


20 


15.940 


.4850 


94 


74.918 


1.3945 


69 


54.993 


1.2583 


44 


35.068 


1.1051 


19 


15.143 


.4820 


93 


74.121 


1.3882 


68 


54.196 


1.2523 


43 


34.271 


1.0993 


18 


14.346 


.4790 


92 


73.324 


.3833 


67 


53.399 


1.2462 


42 


33.474 


1.0935 


17 


13.549 


.4760 


91 


72.527 


.3783 


66 


52.602 


1.2402 


41 


32.677 


1.0878 


16 


12.752 


.4730 


90 


71.730 


.3732 


65 


51.805 


1.2341 


40 


31.880 


1.0821 


15 


11.955 


.4700 


89 


70.933 


.3681 


64 


51.068 


1.2277 


39 


31.083 


1.0764 


14 


11.158 


.4670 


88 


70.136 


.3630 


63 


50.211 


1.2212 


38 


30.286 


1.0708 


13 


10.361 


.4640 


87 


69.339 


.3579 


62 


49.414 


.2148 


37 


29.489 


.0651 


12 


9.564 


.4600 


86 


68.542 


.3529 


61 


48.617 


.2084 


36 


28.692 


.0595 


11 


8.767 


.4570 


85 


67.745 


.3477 


60 


47.820 


.2019 


35 


27.895 


.0540 


10 


7.970 


.4530 


84 


66.948 


.3427 


59 


47.023 


.1958 


34 


27.098 


.0485 


9 


7.173 


.4500 


83 


66.155 


.3376 


58 


46.226 


.1895 


33 


26.301 


.0430 


8 


6.376 


.4460 


82 


65.354 


.3323 


57 


45.429 


.1833 


32 


25.504 


.0375 


7 


5.579 


.4424 


81 


64.557 


.3270 


56 


44.632 


.1770 


31 


24.707 


.0320 


6 


4.782 


.4385 


80 


63.760 


.3216 


55 


43.835 


.1709 


30 


23.900 


.0267 


5 


3.985 


.4346 


79 


62.963 


.3163 


54 


43.038 


.1648 


29 


23.113 


.0212 


4 


3.188 


.4306 


78 


62.166 


.3110 


53 


42.241 


.1587 


28 


22.316 


1.0159 


3 


2.391 


.4269 


77 


61.369 


.3056 


52 


41.444 


.1526 


27 


21.519 


1.0106 


2 


1.594 


.4228 


76 


60.572 


.3001 


51 


40.647 


.1465 


26 


20.722 


1.0053 


J 


0.797 



The column of dry acid shows the weight 
which any salifiable base would gain, by unit- 
ing with 100 parts of the liquid acid of the 
corresponding specific gravity. But it may be 
proper here to observe, that Sir H. Davy, in 
extending his views relative to the constitution 
of the dry muriates, to the nitrates, has sug- 
gested, that the latter when dry may be con- 
sidered as consisting, not of a dry nitric acid 
combined with the salifiable oxide, but of the 
oxygen and nitrogen of the nitric acid with 
the metal itself in triple union. A view of 
his reasoning will be found under the article 
SALT. He regards liquid nitric acid, at its 
utmost density, as a compound of 1 prime of 
hydrogen, 1 of nitrogen, and 6 of oxygen. 

The strongest acid that Mr Kirwan could 
procure at 60 was 1.5543; but Rouelle pro- 
fesses to have obtained it of 1.583. 

Nitric acid should be of the specific gra- 
vity of 1.5, or a little more, and colourless. 

That of Mr Kirwan seems to have con- 
sisted of one prime of real acid and one of 
water, when the suitable corrections are made; 



but no common chemical use requires jt of 
such a strength. 

The Atomical Relationships of Acid and 
Water were thus presented by me, in a ta- 
bular form, in the Journal of Science for 
January 1819, p. 248. 



Liquid Acid 
of 1.5. 


Sp. Grav. 


Atoms 
dry Acid. 


Atoms 
Water. 


100 


.5000 


100 


152 


98 


.4960 


100 


168 


96 


.4910 


100 


183 


94 


.4850 


100 


200 


92 


.4790 


100 


216 


90 


.4730 


100 


236 


86 


.4600 


100 


275 


84 


.4530 


100 


294 


83i nearly. 


. . 


100 


300 


83 


.4500 


100 


305 


57J 


.3340 


100 


700 


47 


.2765 


100 


1000 



ACID 



NITRIC. 



The following Table of boiling points has 
been given by Mr Dalton. 



Acid of sp. gr. 



,50 boils at 210 



.45 

.42 

.40 

.35 

.30 

1.20 

1.15 



240 
248 
247 
242 
236 
226 
219 



At 1.42 specific gravity it distils unaltered. 
Stronger acid than that becomes weaker, and 
weaker acid stronger, by boiling. When the 
strong acid is cooled down to 60, it con- 
cretes, by slight agitation, into a mass of the 
consistence of butter. 

This acid is eminently corrosive, and hence 
its old name of aquafortis. Its taste is sour 
and acrid. It is a deadly poison when in- 
troduced into the stomach in a concentrated 
state, but when greatly diluted, it may be 
swallowed without inconvenience. It is often 
contaminated, through negligence or fraud 
in the manufacturer, with sulphuric and mu- 
riatic acids. Nitrate of lead detects both ; or 
nitrate of baryta may be employed to deter- 
mine the quantity of sulphuric acid, and ni- 
trate of silver that of the muriatic. The lat- 
ter proceeds from the crude nitre usually 
containing a quantity of common salt. 

When it is passed through a red-hot por- 
celain tube, it is resolved into oxygen and 
nitrogen, in the proportion above stated. It 
retains its oxygen with little force, so that it 
is decomposed by all combustible bodies. 
Brought into contact with hydrogen gas at 
a high temperature, a violent detonation en- 
sues; so that this must not be done without 
great caution. It inflames essential oils, as 
those of turpentine and cloves, when sudden- 



Co LOUR. 
Pale yellow, 
Bright yellow, 
Dark orange, 
Light olive, 
Dark olive, 
Bright green, 
Blue green, 



REAL ACID. 
90.5 
88.94 
86.84 
86.0 
85.4 
84.8 
84.6 



But these colours are not exact indications 
of the state of the acid ; for an addition of 
water will change the colour into one lower 
in the scale, so that a considerable portion of 
water will change the dark orange to a blue- 
green. 

Nitric acid is of considerable use in the 
arts. It is employed for etching on copper ; 
as a solvent of tin, to form with that metal a 
mordant for some of the finest dyes ; in me- 
tallurgy and assaying; in various chemical 
processes, on account of the facility with 
which it parts with oxygen and dissolves me- 



ly poured on them ; but, to perform this ex- 
periment with safety, the acid must be pour- 
ed out of a bottle tied to the end of a long 
stick, otherwise the operator's face and eyes 
will be endangered. If it be poured on per- 
fectly dry charcoal powder, it excites com- 
bustion, with the emission of copious fumes. 
By boiling it with sulphur it is decomposed, 
and its oxygen, uniting with the sulphur, 
forms sulphuric acid. 

Proust has ascertained, that acid having 
the specific gravity 1.48, has no more action 
on tin than on sand, while acid somewhat 
stronger or weaker acts furiously on the 
metal. Now, acid of 1.485, by my table, 
consists of one prime of real acid united with 
two of water, constituting, it would thus ap- 
pear, a peculiarly powerful combination. 

Acid which takes up T V 5 8 o of its wei g ht 
of marble, freezes, according to Mr Caven- 
dish, at 2. When it can dissolve T 5 oVo> 
it requires to be cooled to 41. 6 before 
congelation ; and when so much diluted as 
to take up only T Vo"o lt congeals at 
40. 3. The first has a specific gravity of 
1.330 nearly, and consists of 1 prime of dry 
acid -j- 7 of water ; the second has a specific- 
gravity of 1.420, and contains exactly 1 prime 
of dry acid -|- 4 of water ; while the third 
has a specific gravity of 1.215, consisting of 
1 prime of acid -f 14 of water. We per- 
ceive, that the liquid acid of 1.420, composed 
of 4 primes of water -f- 1 of dry acid, pos- 
sesses the greatest power of resisting the in- 
fluence of temperature to change its state. 
It requires the maximum heat to boil it, 
when it distils unchanged; and the maxi- 
mum cold to effect its congelation. 

The colour of the acid is affected by the 
quantity of nitric oxide it holds, and Sir H. 
Davy has given us the following Table of 
proportions answering to its different hues. 



NITRIC OXIDE. 
1.2 
2.96 
5.56 
6.45 
7.1 
7.76 
8. 



WATER. 
8.3 
8.10 
7.6 
7.55 
7.5 
7.44 
7.4 



tals ; in medicine as a tonic, as also in form 
of vapour to destroy contagion. For the 
purposes of the arts it is commonly used in 
a diluted state, and contaminated with the 
sulphuric and muriatic acids, by the name of 
aquafortis. Two kinds are found in the 
shops one called double aquafortis, which is 
about half the strength of nitric acid ; the 
other simply aquafortis, which is half the 
strength of the double. 

A compound made by mixing two parts of 
the nitric acid with one of muriatic, known 
formerly by the name of aqua regia, and now 



ACID 



77 



NITRIC. 



by that of nitro-muriatic acid, has the pro- 
perty of dissolving gold and platina. On 
mixing the two acids, heat is given out, an 
effervescence takes place, and the mixture 
acquires an orange colour. This is likewise 
made by adding gradually to an ounce of 
powdered muriate of ammonia four ounces 
of double aquafortis, and keeping the mix- 
ture in a sand heat till the salt is dissolved ; 
taking care to avoid the fumes, as the vessel 
must be left open : or by distilling nitric acid 
with an equal weight, or rather more, of 
common salt. 

On this subject we are indebted to Sir H. 
Davy for some excellent observations, pub- 
lished by him in the first volume of the Jour- 
nal of Science. If strong nitrous acid, satu- 
rated with nitrous gas, be mixed with a satu- 
rated solution of muriatic acid gas, no other 
effect is produced than might be expected 
from the action of nitrous acid of the same 
strength on an equal quantity of water ; and 
the mixed acid so formed has no power of 
action on gold or platina. Again, if mu- 
riatic acid gas, and nitrous gas, in equal 
volumes, be mixed together over mercury, 
and half a volume of oxygen be added, the 
immediate condensation will be no more than 
might be expected from the formation of 
nitrous acid gas. And when this is decom- 
posed, or absorbed by the mercury, the mu- 
riatic acid gas is found unaltered, mixed with 
a certain portion of nitrous gas. 

It appears then that nitrous acid, and mu- 
riatic acid gas, have no chemical action on 
each other. If colourless nitric acid and mu- 
riatic acid of commerce be mixed together, 
the mixture immediately becomes yellow, and 
gains the power of dissolving gold and plati- 
num. If it be gently heated, pure chlorine 
arises from it, and the colour becomes deeper. 
If the heat be longer continued, chlorine still 
rises, but mixed with nitrous acid gas. When 
the process has been very long continued, till 
the colour becomes very deep, no more chlo- 
rine can be procured, and it loses its power of 
acting upon platinum and gold. It is now 
nitrous and muriatic acids. It appears then 
from these observations, which have been very 
often repeated, that nitro-muriatic acid owes 
its peculiar properties to a mutual decompo- 
sition of the nitric and muriatic acids ; and 
that water, chlorine, and nitrous acid gas, are 
the results. Though nitrous gas and chlo- 
rine have no action on each other when per- 
fectly dry, yet if water be present there is an 
immediate decomposition, and nitrous acid 
and muriatic acid are formed. 118 parts of 
strong liquid nitric acid being decomposed in 
this case, yield 67 of chlorine. Aqua regia 
does not oxidize gold or platina : it merely 
causes their combination with chlorine. 

A bath made of nitro-muriatic acid, dilut- 
ed so much as to taste no sourer than vine- 
gar, or of such a strength as to prick the skin 



a little after being exposed to it for twenty 
minutes or half an hour, has been introduced 
by Dr Scott of Bombay as a remedy in chro- 
nic siphylis, a variety of ulcers and diseases 
of the skin, chronic hepatites, bilious disposi- 
tions, general debility, and languor. He con- 
siders every trial as quite inconclusive where 
a ptyalism, some affection of the gums, or 
some very evident constitutional effect, has 
not arisen from it. The internal use of the 
same acid has been recommended to be con- 
joined with that of the partial or general 
bath. 

With the different bases the nitric acid 
forms nitrates. 

Nitrate of baryta, when perfectly pure, is 
in regular oetaedral crystals, though it is 
sometimes obtained in small shining scales. 
It may be prepared by uniting baryta direct- 
ly with nitric acid, or by decomposing the 
carbonate or sulphuret of baryta with this 
acid. Exposed to heat it decrepitates, and 
at length gives out its acid, which is decom- 
posed ; but if the heat be urged too far, the 
baryta is apt to vitrify with the earth of the 
crucible. It is soluble in 12 parts of cold, 
and 3 or 4 of boiling water. It is said to 
exist in some mineral waters. It consists of 
6. 75 acid 4- 9.75 base. 

Nitrate of potash is the salt well known 
by the name of nitre or saltpetre. It is found 
ready formed in the East Indies, in Spain, in 
the kingdom of Naples, and elsewhere, in 
considerable quantities : but nitrate of lime is 
still more abundant. Far the greater part of 
the nitrate made use of is produced by a com- 
bination of circumstances which tend to com- 
pose and condense nitric acid. This acid ap- 
pears to be produced in all situations where 
animal matters are completely decomposed 
with access of air, and of proper substances 
with which it can readily combine. Grounds 
frequently trodden by cattle, and impregnated 
with their excrements, or the walls of inha- 
bited places where putrid animal vapours 
abound, such as slaughter-houses, drains, or 
the like, afford nitre by long exposure to the 
air. Artificial nitre beds are made by an at- 
tention to the circumstances in which this salt 
is produced by nature. Dry ditches are dug, 
and covered with sheds, open at the sides, to 
keep off the rain : these are filled with animal 
substances such as dung, or other excre- 
ments, with the remains of vegetables, and 
old mortar, or other loose calcareous earth ; 
this substance being found to be the best and 
most convenient receptacle for the acid to 
combine with. Occasional watering, and 
turning up from time to time, are necessary 
to accelerate the process, and increase the 
surfaces to which the air may apply ; but too 
much moisture is hurtful. When a certain 
portion of nitrate is formed, the process ap- 
pears to go on more quickly ; but a certain 
quantity stops it altogether ; and after this 



ACID 



78 



NITRIC. 



cessation the materials will go on to furnish 
more, if what is formed be extracted by lixi- 
viation. After a succession of many months, 
more or less, according to the management 
of the operation, in which the action of a re- 
gular current of fresh air is of the greatest 
importance, nitre is found in the mass. If 
the beds contained much vegetable matter, a 
considerable portion of the nitrous salt will 
be common saltpetre; but if otherwise, the 
acid will, for the most part, be combined 
with the calcareous earth. 

To extract the saltpetre from the mass of 
earthy matter, a number of large casks are 
prepared, with a cock at the bottom of each, 
and a quantity of straw within, to prevent its 
being stopped up. Into these the matter is 
put, together with wood-ashes, either strewed 
at top, or added during the filling. Boiling 
water is then poured on, and suffered to stand 
for some time ; after which it is drawn off, 
and other water added in the same manner, 
as long as any saline matter can be thus ex- 
tracted. The weak brine is heated, and pass- 
ed through other tubs, until it becomes of 
considerable strength. It is then carried to 
the boiler, and contains nitre and other salts ; 
the chief of which is common culinary salt, 
and sometimes muriate of magnesia. It is 
the property of nitre to be much more soluble 
in hot than cold water ; but common salt is 
very nearly as soluble in cold as in hot water. 
Whenever, therefore, the evaporation is car- 
ried by boiling to a certain point, much of 
the common salt will fall to the bottom, for 
want of water to hold it in solution, though 
the nitre will remain suspended by virtue of 
the heat. The common salt thus separated 
is taken out with a perforated ladle, and a 
small quantity of the fluid is cooled, from 
time to time, that its concentration may be 
known by the nitre which crystallizes in it. 
When the fluid is sufficiently evaporated, it 
is taken out and cooled, and great part of the 
nitre separates in crystals ; while the remain- 
ing common salt continues dissolved, because 
equally soluble in cold and in hot water. 
Subsequent evaporation of the residue will 
separate more nitre in the same manner. By 
the suggestion of Lavoisier, a much simpler 
plan was adopted; reducing the crude nitre 
to powder, and washing it twice with water. 
This nitre, which is called nitre of the first 
boiling, contains some common salt; from 
which it might be purified by solution in a 
small quantity of water, and subsequent eva- 
poration : for the crystals thus obtained are 
much less contaminated with common salt 
than before ; because the proportion of water 
is so much larger, with respect to the small 
quantity contained by the nitre, that very lit- 
tle of it will crystallize. For nice purposes, 
the solution and crystallization of nitre are 
repeated four times. The crystals of nitre 
are usually of the form of six-sided flattened 



prisms, with diedral summits. Its taste is 
penetrating ; but the cold produced by plac- 
ing the salt to dissolve in the mouth, is such 
as to predominate over the real taste at first. 
Seven parts of water dissolve two of nitre, at 
the temperature of 60; but boiling water 
dissolves its own weight. 100 parts of alco- 
hol, at a heat of 176, dissolve only 2.9. Its 
constituents are nitric acid 6.75-f- potash 6. 

On being exposed to a gentle heat, nitre 
fuses; and in this state being poured into 
moulds, so as to form little round cakes or 
balls, it is called sal prunella, or crystal mi- 
neral. 

This salt powerfully promotes the com- 
bustion of inflammable substances. Two or 
three parts mixed with one of charcoal, and 
set on fire, burn rapidly ; azote and carbonic 
acid gas are given out ; and a small portion 
of the latter is retained by the alkaline resi- 
duum, which was formerly called clyssus of 
nitre. Three parts of nitre, two of subcar- 
bonate of potash, and one of sulphur, mixed 
together in a warm mortar, form the fulmi- 
nating powder ; a small quantity of which, 
laid on a fire shovel, and held over the fire 
till it begins to melt, explodes with a loud 
sharp noise. Mixed with sulphur and char- 
coal it forms gunpowder. See GUNPOWDER. 

Three parts of nitre, one of sulphur, and 
one of fine saw-dust, well mixed, constitute 
what is called the powder of fusion. If a 
bit of base copper be folded up and covered 
with this powder in a walnut-shell, and the 
powder be set on fire with a lighted paper, 
it will detonate rapidly, and fuse the metal 
into a globule of sulphuret without burning 
the shell. 

Silex, alumina, and baryta, decompose 
this salt in a high temperature, by uniting 
with its base. The alumina will effect this 
even after it has been made into pottery. 

The uses of nitre are various. Beside 
those already indicated, it enters into the 
composition of fluxes, and is extensively em- 
ployed in metallurgy; it serves to promote 
the combustion of sulphur in fabricating its 
acid ; it is used in the art of dyeing ; it is 
added to common salt for preserving meat, 
to which it gives a red hue ; it is an ingre- 
dient in some frigorific mixtures; and it is 
prescribed in medicine, as cooling, febrifuge, 
and diuretic ; and some have recommended 
it, mixed with vinegar, as a very powerful 
remedy for the sea scurvy. 

Nitrate of soda, formerly called cubic or 
quadrangular nitre, approaches in its proper- 
ties to the nitrate of potash ; but differs from 
it in being somewhat more soluble in cold 
water, though less in hot, which takes up 
little more than its own weight; in being 
inclined to attract moisture from the atmos- 
phere ; and in crystallizing in rhombs, or 
rhomboidal prisms. It may be prepared by 
saturating soda with the nitric acid ; by pre- 



ACID 



NITRIC. 



cipitating nitric solutions of the metals, or 
of the earths, except baryta, by soda; by 
lixiviating and crystallizing the residuum of 
common salt distilled with three-fourths its 
weight of nitric acid ; or by saturating the 
mother waters of nitre with soda, instead of 
potash. 

This salt has been considered as useless ; 
but Professor Proust says, that five parts of 
it, with one of charcoal and one of sulphur, 
will burn three times as long as common 
powder, so as to form an economical com- 
position for fire-works. It consists of 6.75 
acid -f- 4> soda. 

Nitrate of strontia may be obtained in the 
same manner as that of baryta, with which 
it agrees in the shape of its crystals, and most 
of its properties. It is much more soluble, 
however, requiring but four or five parts of 
water according to Vauquelin, and only an 
equal weight according to Mr Henry. Boil- 
ing water dissolves nearly twice as much as 
cold. Applied to the wick of a candle, or 
added to burning alcohol, it gives a deep red 
colour to the flame. On this account it is 
useful in the art of pyrotechny. It consists 
of 6.75 acid -j- 6.5 strontia. 

Nitrate of lime, the calcareous nitre of 
older writers, abounds in the mortar of old 
buildings, particularly those that have been 
much exposed to animal effluvia, or pro- 
cesses in which azote is set free. Hence it 
abounds in nitre beds, as was observed when 
treating of the nitrate of potash. It may 
also be prepared artificially, by pouring dilute 
nitric acid on carbonate of lime. If the 
solution be boiled down to a syrupy consis- 
tence, and exposed in a cool place, it crys- 
tallizes in long prisms, resembling bundles 
of needles diverging from a centre. These 
are soluble, according to Henry, in an equal 
weight of boiling water, and twice their 
weight of cold ; soon deliquesce on exposure 
to the air, and are decomposed at a red heat. 
Fourcroy says, that cold water dissolves four 
times its weight, and that its own water of 
crystallization is sufficient to dissolve it at a 
boiling heat. It is likewise soluble in less 
than its weight of alcohol. By evaporating 
the aqueous solution to dryness, continuing 
the heat till the nitrate fuses, keeping it in 
this state five or ten minutes, and then pour- 
ing it into an iron pot previously heated, we 
obtain Baldiviiis phosphorus. This, which 
is perhaps more properly nitrate of lime, 
being broken to pieces, and kept in a phial 
closely stopped, will emit a beautiful white 
light in the dark, after having been exposed 
some time to the rays of the sun. At pre- 
sent no use is made of this salt, except for 
drying some of the gases by attracting their 
moisture ; but it might be employed instead 
of the nitrate of potash for manufacturing 
aquafortis. 

Nitrate of ammonia possesses the property 



of exploding, and being totally decomposed, 
at the temperature of 600 ; whence it ac- 
quired the name of nitrumjlammans. The 
readiest mode of preparing it is by adding 
carbonate of ammonia to dilute nitric acid 
till saturation takes place. If this solution 
be evaporated in a heat between 70 and 
100, and the evaporation not carried too 
far, it crystallizes in hexaedral prisms termi- 
nating in very acute pyramids : if the heat 
rise to 212, it will afford, on cooling, long 
fibrous silky crystals : if the evaporation be 
carried so far as for the salt to concrete im- 
mediately on a glass rod by cooling, it will 
form a compact mass. According to Sir 
H. Davy, these differ but little from each 
other, except in the water they contain, their 
component parts being as follows : 



Compact 



74.5 



18.4 rl2.1 

19.3 water -J 8.2 
19.8 L 5.7 



All these are completely deliquescent, but 
they differ a little in solubility. Alcohol at 
176 dissolves nearly 90.9 of its own weight. 

When dried as much as possible without 
decomposition, it consists of 6.75 acid + 
2.125 ammonia -j- 1.125 water. 

The chief use of this salt is for affording 
nitrous oxide on being decomposed by heat. 
See NITROGEN- ( OXIDE of). 

Nitrate of magnesia, magnesian nitre, crys- 
tallizes in four- sided rhomboidal prisms, with 
oblique or truncated summits, and sometimes 
in bundles of small needles. Its taste is bit- 
ter, and very similar to that of nitrate of lime, 
but less pungent. It is fusible, and decom- 
posable by heat, giving out first a little oxy- 
gen gas, then nitrous oxide, and lastly nitric 
acid. It deliquesces slowly. It is soluble 
in an equal weight of cold water, and in but 
little more of hot, so that it is scarcely crys- 
tallizable but by spontaneous evaporation. 

The two preceding species are capable of 
combining into a triple salt, an ammoniaco- 
magnesian nitrate, either by uniting the two 
in solution, or by a partial decomposition of 
either by means of the base of the other. 
This is slightly inflammable when suddenly 
heated ; and by a lower heat is decomposed, 
giving out oxygen, azote, more water than it 
contained nitrous oxide, and nitric acid. The 
residuum is pure magnesia. It is disposed 
to attract moisture from the air, but is much 
less deliquescent than either of the salts that 
compose it, and requires eleven parts of water 
at 60 to dissolve it. Boiling water takes up 
more, so that it will crystallize by cooling. 
It consists of 78 parts of nitrate of magnesia, 
and 22 of nitrate of ammonia. 

From the activity of the nitric acid as a 
solvent of earths in analysis, the nitrate of 
glucina is better known than any other of 
the salts of this new earth. Its form is 
either pulverulent, or a tenacious or ductile 



ACID 



80 



NITRIC, OXYGENIZED. 



mass. Its taste is at first saccharine, and 
afterwards astringent. It grows soft by ex- 
posure to heat, soon melts ; its acid is decom- 
posed into oxygen and azote, and its base 
alone is left behind. It is very soluble, and 
very deliquescent. 

Nitrate, or rather supernitrate, of alumina 
crystallizes, though with difficulty, in thin, 
soft, pliable flakes. It is of an austere and 
acid taste, and reddens blue vegetable colours. 
It may be formed by dissolving in diluted 
nitric acid, with the assistance of heat, fresh 
precipitated alumina, well washed but not 
dried. It is deliquescent, and soluble in a 
very small portion of water. Alcohol dis- 
solves its own weight. It is easily decom- 
posed by heat. 

Nitrate of zirconia was first discovered by 
Klaproth, and has since been examined by 
Guyton-Morveau and Vauquelin. Its crys- 
tals are small, capillary, silky needles. Its 
taste is astringent It is easily decomposed 
by fire, very soluble in water, and deliques- 
cent. It may be prepared by dissolving zir- 
conia in strong nitric acid ; but, like the pre- 
ceding species, the acid is always in excess. 

Nitrate of yttria may be prepared in a 
similar manner. Its taste is sweetish and 
astringent. It is scarcely to be obtained in 
crystals; and if it be evaporated by too 
strong a heat, the salt becomes soft like 
honey, and on cooling concretes into a stony 
mass. See SALT. 

ACID (NITROUS). This acid is ob- 
tained by exposing nitrate of lead to heat in 
a glass retort. Pure nitrous acid comes over 
in the form of an orange-coloured liquid. 
It is so volatile as to boil at the temperature 
of 82. Its specific gravity is 1.450. When 
mixed with water it is decomposed, and ni- 
trous gas is disengaged, occasioning efferves- 
cence. It is composed of one volume of 
oxygen united with two of nitrous gas. It 
therefore consists ultimately, by weight, of 
1.75 nitrogen -|- 4 oxygen ; by measure, of 
2 oxygen -}- 1 nitrogen. The various co- 
loured acids of nitre are not nitrous acids, but 
nitric acid impregnated with nitrous gas, the 
deutoxide of nitrogen or azote. (See the 
preceding table of Sir H. Davy, concerning 
the coloured acid). 

ACID (H YPONITROUS). It appears, 
from the experiments of M. Gay Lussac, 
that there exists a third acid, formed of 100 
azote and 150 oxygen. When into a test 
tube filled with mercury, we pass up from 
500 to 600 volumes of deutoxide of azote, a 
little alkaline water, and 100 parts of oxygen 
gas, we obtain an absorption of 500, pro- 
ceeding from the condensation of the 100 
parts of oxygen with 400 of deutoxide of 
azote. Now these 400 parts are composed of 
200 azote and 200 oxygen ; consequently the 
new acid is composed of azote and oxygen in 
the ratio of 100 to 1 50, as we have said above. 



It is the same acid, according to M. Gay 
Lussac, which is produced on leaving for a 
long time a strong solution of potash in con- 
tact witli deutoxide of azote. At the end of 
three months he found that 100 parts of 
deutoxide of azote were reduced to 25 of 
protoxide of azote, and that crystals of hypo- 
nitrite (pernitrite) were formed. 

Hyponitrous acid (called pernitrous by the 
French chemists) cannot be insulated. As 
soon as we lay hold, by an acid, of the pot- 
ash with which it is associated, it is trans- 
formed into deutoxide of azote, which is dis- 
engaged, and into nitrous or nitric acid, which 
remains in solution. 

ACID (NITRO-LEUCIC). Leucine is 
capable of uniting to nitric acid, and forming 
a compound, which M. Braconnot has called 
the nitro-leucic acid. When we dissolve 
leucine in nitric acid, and evaporate the so- 
lution to a certain point, it passes into a crys- 
talline mass, without any disengagement of 
nitrous vapour, or of any gaseous matter: 
If we press this mass between blotting paper, 
and redissolve it in water, we shall obtain 
from this, by concentration, fine, divergent, 
and nearly colourless needles. These con- 
stitute the new acid. It unites to the bases 
forming salts, which fuse on red-hot coals. 
The nitro-leucates of lime and magnesia are 
unalterable in the air. 

ACID(NITRO-SACCHARIC). When 
we heat the sugar of gelatin with nitric acid, 
it dissolves without any apparent disengage- 
ment of gas ; and if we evaporate this solution 
to a proper degree, it forms, on cooling, a 
crystalline mass. On pressing this mass be- 
tween the folds of blotting paper, and recrys- 
tallizing them, we obtain beautiful prisms, 
colourless, transparent, and slightly striated. 
These crystals are very different from those 
which serve to produce them ; constitute, ac- 
cording to M. Braconnot, a true acid, which 
results from the combination of the nitric acid 
itself, with the sweet matter of which the first 
crystals are formed. M. Thenard conceives 
it is the nitrous acid which is present. 

Nitro-saccharic acid has a taste similar to 
that of the tartaric ; only it is a little sweetish. 
Exposed to the fire in a capsule, it froths 
much, and is decomposed with the diffusion 
of a pungent smell. Thrown on burning coals 
it acts like saltpetre. It produces no change 
in saline solutions. Finally, it combines with 
the bases, and gives birth to salts which pos- 
sess peculiar properties. For example, the salt 
which it forms with lime is not deliquescent, 
and is very little soluble in strong alcohol. 
That which it produces with the oxide of lead 
detonates to a certain degree by the action of 
heat. Ann. de Chimie et de Phys. xiii. 1 13. 

ACID (NITRIC, OXYGENIZED). 
In our general remarks on acidity, we have 
described M. Thenard's newly discovered me- 
thod of oxygenizing the liquid acids. The 



ACID 



Hi 



OLEIC. 



first that he examined was the combination 
of nitric acid and oxygen. When the per- 
oxide of barium, prepared by saturating ba- 
ryta with oxygen, is moistened, it falls to 
powder without much increase of tempera- 
ture. If in this state it by mixed with seven 
or eight times its weight of water, and dilute 
nitric acid be gradually poured upon it, it 
dissolves gradually by agitation, without the 
evolution of any gas. The solution is neu- 
tral, or has no action on turnsole or turmeric. 
When we add to this solution the requisite 
quantity of sulphuric acid, a copious precipi- 
tate of sulphate of baryta falls, and the filtered 
liquor is merely water, holding in solution 
oxygenized nitric acid. This acid is liquid 
and colourless ; it strongly reddens turnsole, 
and resembles in all its properties nitric acid. 
When heated it immediately begins to dis- 
charge oxygen ; but its decomposition is never 
complete, unless it be kept boiling for some 
time. The only method which M. Thenard 
found successful for concentrating it, was to 
place it in a capsule, under the receiver of 
an air-pump, along with another capsule full 
of lime, and to exhaust the receiver. By this 
means he obtained an acid sufficiently con- 
centrated to give out eleven times its bulk of 
oxygen gas. 

This acid combines very well with baryta, 
potash, soda, ammonia, and neutralizes them. 
When crystallization commences in the liquid, 
by even a spontaneous evaporation, these salts 
are instantly decomposed. The exhausted re- 
ceiVer also decomposes them. The oxygenized 
nitrates, when changed into common nitrates, 
do not change the state of their neutraliza- 
tion. Strong solution of potash poured into 
their solutions decomposes them. 

Oxygenized nitric acid does not act on 
gold ; but it dissolves all the metals which 
the common acid acts on, and when it is not 
too concentrated, it dissolves them without 
effervescence. Deutoxide or peroxide of ba- 
rium contains just double the proportion of 
oxygen that its protoxide does. But M. 
Thenard says, that the baryta obtained from 
the nitrate by ignition contains always a little 
of the peroxide. When oxygenized nitric 
acid is poured upon oxide of silver, a strong 
effervescence takes place, owing to the dis- 
engagement of oxygen. One portion of the 
oxide of silver is dissolved ; the other is re- 
duced at first, and then dissolves likewise, 
provided the quantity of acid be sufficient. 
The solution being completed, if we add pot- 
ash to it, by little and little, a new efferves- 
cence takes place, and a dark violet precipi- 
tate falls ; at least this is always the colour 
of the first deposit. It is insoluble in am- 
monia, and, according to all appearance, is a 
protoxide of silver. 

As soon as we plunge a tube containing 
oxide of silver into a solution of oxygenized 
nitrate of potash, a violent effervescence takes 



place, the oxide is reduced, the silver preci- 
pitates, the whole oxygen of the oxygenized 
nitrate is disengaged at the same time with 
that of the oxide ; and the solution, which 
contains merely common nitrate of potash, 
remains neutral, if it was so at first. But 
the most unaccountable phenomenon is the 
following : If silver, in a state of extreme 
division (fine filings), be put into the oxy- 
genized nitrate, or oxygenized muriate of 
potash, the whole oxygen is immediately dis- 
engaged. The silver itself is not attacked, 
and the salt remains neutral as before. Iron, 
zinc, copper, bismuth, lead, and platinum, 
likewise possess this property of separating 
the oxygen of the. oxygenized nitrate. Iron 
and zinc are oxidized, and at the same time 
occasion the evolution of oxygen. The other 
metals are not sensibly oxidized. They were 
all employed in the state of filings. Gold 
scarcely acts. The peroxides of manganese 
and of lead decompose these oxynitrates. A 
very small quantity of these oxides, in powder, 
is sufficient to drive off the whole oxygen 
from the saline solution. The effervescence 
is lively. The peroxide of manganese un- 
dergoes no alteration. 

Though nitric acid itself has no action on 
the peroxides of lead and manganese, the 
oxygenized acid dissolves both of them with 
the greatest facility. The solution is accom- 
panied by a great disengagement of oxygen 
gas. The effect of silver, he thinks, may 
probably be ascribed to voltaic electricity. 

The remarks appended to our account of 
M. Thenard's oxygenized muriatic acid are 
equally applicable to the nitric ; but the phe- 
nomena are too curious to be omitted in a 
work of the present kind. 

ACID (OLEIC). When potash and hog's 
lard are saponified, the margarate of the al- 
kali separates in the form of a pearly-looking 
solid, while the fluid fat remains in solution, 
combined with the potash. When the alkali 
is separated by tartaric acid, the oily prin- 
ciple of fat is obtained, which M. Chevreul 
purifies by saponifying it again and again, 
recovering it two or three times ; by which 
means the whole of the margarine is sepa- 
rated. As this oil has the property of sa- 
turating bases, and forming neutral com- 
pounds, he has called it oleic acid. In his 
sixth memoir, he gives the following table of 
results : 

100 Oleic acid of human fat 
Saturate Baryta, Strontia, Lead, 

26.00 19.41 82.48 

100 Oleic acid of sheep fat 

26.77 19.38 81.81 

100 Oleic acid of ox fat 

28.93 19.41 81.81 

100 Oleic acid of goose fat 

26.77 19.38 81.34 

100 Oleic acid of hog fat 

27.00 29.38 81.80 



ACID 



OXALIC. 



Oleic acid is an oily fluid without taste 
and smell. Its specific gravity is 0.914. It 
is generally soluble in its own weight of boil- 
ing alcohol, of the specific gravity of 0.7952 ; 
but some of the varieties are still more solu- 
ble. 100 of the oleic acid saturate 16.58 of 
potash, 10.11 of soda, 7.52 of magnesia, 
14.83 of zinc, and 13.93 peroxide of copper. 
M. Chevreul's experiments have finally in- 
duced him to adopt the quantities of 100 acid 
to 27 baryta, as the most correct; whence 
calling baryta 9.75, we have the equivalent 
prime of oleic acid = 36.0. 

ACID (OXALIC). This acid may be 
obtained from sugar in the following way : 
To six ounces of nitric acid in a stoppered 
retort, add, by degrees, one ounce of lump 
sugar coarsely powdered. A gentle heat may 
be applied during the solution, and nitric 
oxide will be evolved in abundance. When 
the whole of the sugar is dissolved, distil off 
a part of the acid, till what remains in the 
retort has a syrupy consistence ; and this will 
form regular crystals, amounting to 58 parts 
from 100 of sugar. These crystals must be 
dissolved in water, recrystallized, and dried 
on blotting paper. 

Many other substances afford the oxalic- 
acid when treated by distillation with the ni- 
tric. Bergman procured it from honey, gum- 
arabic, alcohol, and the calculous concre- 
tions in the kidneys and bladders of animals. 
Scheele and Hermbstadt from sugar of milk. 
Scheele from a sweet matter contained in fat 
oils, and also from the uncrystallizable part 
of the juice of lemons. Hermbstadt from 
the acid of cherries, and the acid of tartar. 
Goettling from beech wood. Kohl from the 
residuum in the distillation of ardent spirits. 
Westrumb not only from the crystallized 
acids of currants, cherries, citrons, raspber- 
ries, but also from the saccharine matters of 
these fruits, and from the uncrystallizable 
parts of the acid juices. Hoffmann from the 
juice of the barberry ; and Berthollet from 
silk, hair, tendons, wool ; also from other 
animal substances, especially from the coa- 
gulum of blood, whites of eggs, and likewise 
from the amylaceous and glutinous parts of 
flour. M. Berthollet observes, that the quan- 
tity of the oxalic acid obtained by treating 
wool with nitric acid was very considerable, 
being above half the weight of the wool em- 
ployed. He mentions a difference which he 
observed between animal and vegetable sub- 
stances thus treated with nitric acid, namely, 
that the former yielded, beside ammonia, a 
large quantity of an oil which the nitric acid 
could not decompose ; whereas the oily parts 
of vegetables were totally destroyed by the 
action of this acid ; and he remarks, that in 
this instance the glutinous part of flour re- 
sembled animal substances, whereas the amy- 
laceous part of the flour retained its vegeta- 
ble properties. He further remarks, that the 



quantity of oxalic acid furnished by vegetable 
matters thus treated is proportionable to their 
nutritive quality, and particularly, that from 
cotton he could not obtain any sensible quan- 
tity. Deyeux, having cut with scissars the 
hairs of the chick pea, found they gave out 
an acid liquor, which, on examination, proved 
to be an aqueous solution of pure oxalic acid. 
Proust, and other chemists, had before ob- 
served, that the shoes of persons walking 
through a field of chick peas were corroded. 

Braconnot has lately shewn, that the crust- 
aceous lichens, such as pertusaria communis, 
urceolaria scruposa, isidium corallinum, pa- 
tellaria tartarea, ventosa rubra, liematomma-, 
bceomices ericetorum, squamaria lentigera, 
placodium radiosum, ochroleucum, psora can-' 
dida, contain nearly one-half their weight of 
oxalate of lime ; a substance which is to these 
plants what carbonate of lime is to corallines, 
and phosphate of lime to animal bones. Hum- 
boldt says, these are the lichens by which the 
earth void of vegetation in the north of Peru 
begins to be covered : by their means vegeta- 
tion seems to commence on the barren sur- 
face of rocks. By the successive action of 
solution of carbonate of soda, aided by a boil- 
ing heat, the oxalate of lime in these plants 
is converted into a carbonate, while oxalate 
of soda remains dissolved. 

M. Vauquelin, by treating pectic acid with 
potash in a crucible, converted it into oxalate 
of potash. This production of oxalic acid 
suggested to M. Gay Lussac the following 
line of experiments : Cotton heated below 
redness, with five times its weight of caustic 
potash and a little water, was converted part- 
ly into oxalate of potash ; as was shewn by 
supersaturating with nitric acid, and testing 
with nitrates of lead and lime. Wood saw- 
dust, with the same treatment, gave the same 
result. So did sugar, starch, gum, and sugar 
of milk, with the disengagement of hydrogen. 
The most remarkable transformation is that 
of tartaric into oxalic acid by potash, at a 
temperature not exceeding 400 F. 

Citric and mucic acids produced also much 
oxalic acid, as did also lithic acid. Silk and 
gelatin gave a similar result Indigo gave 
no oxalic acid. Soda may be used instead 
of potash, but the carbonated alkali will not 
answer. 

From the general phenomena it may be 
concluded, that a vegetable substance, heated 
moderately with potash, gives oxalic acid ; 
but when more strongly heated, carbonic 
acid. 

Tartar may be very elegantly transformed 
into oxalate of potassa, by dissolving the 
rough tartar in water with a proper quantity 
of potash or soda, and making the solution 
pass by means of a pump, in a continual cur- 
rent, through a thick tube of iron or bronze, 
heated to 400 or 450 F. The pressure 
need not be more than 25 atmospheres, for 



ACID 



83 



OXALIC. 



no gas will be disengaged. A valve is to be 
placed at the opposite extremity to that at 
which the solution enters, and charged with 
sufficient weight to obtain this pressure ; it 
will then be opened only by the pressure 
exerted by the injection pump. Less than a 
prime proportion of potassa for a proportion 
of neutral tartar will be necessary. 

Oxalic acid crystallizes in quadrilateral 
prisms, the sides of which are alternately 
broad and narrow, and summits diedral ; or, 
if crystallized rapidly, in small irregular nee- 
dles. They are efflorescent in dry air, but 
attract a little humidity if it be damp ; are 
soluble in one part of hot and two of cold 
water ; and are decomposable by a red heat, 
leaving a small quantity of coaly residuum. 
100 parts of alcohol take up nearly 56 at a 
boiling heat, but not above 40 cold. Their 
acidity is so great, that when dissolved in 
3600 times their weight of water, the solution 
reddens litmus paper, and is perceptibly acid 
to the taste. 

The oxalic acid is a good test for detecting 
lime, which it separates from all the other 
acids, unless they are present in excess. It 
has likewise a greater affinity for lime than 
for any other of the bases, and forms with it 
a pulverulent insoluble salt, not readily de- 
composable except by fire, and turning syrup 
of violets green. 

From the oxalate of lead, Berzelius infers 
its prime equivalent to be 4.552, and by igne- 
ous decomposition he finds it resolved into 
66.534 oxygen, 33.222 carbon, and 0.244 
hydrogen. Since Berzelius published his ana- 
lysis, oxalic acid has been made the subject 
of some ingenious remarks by Dobereiner, in 
the 16th vol. of Schweigger's Journal. We 
see that the carbon and oxygen are to each 
other in the simple ratio of one or two ; or re- 
ferred to their prime equivalent, as two of car- 
bon = 1.5, to three of oxygen = 3.0. This 
proportion is what would result from a prime 
of carbonic acid = C -|- 2. O, combined 
with one of carbonic oxide, = C -|- O. C, 
being carbon, and O oxygen. The sum of 
the above weights gives 4.5 for the prime 
equivalent of oxalic acid, disregarding hy- 
drogen, which constitutes but l-37th of the 
whole, and may be referred to the imperfect 
desiccation of the oxalate of lead subjected 
to analysis. 

I have found in my experiments (Phil. 
Trans. 1822), that dry oxalate of lead ignited 
in contact with calomel in a glass tube, yields 
no trace of muriatic acid ; a certain proof that 
no hydrogen exists in dry oxalic acid. I 
found the prime equivalent of oxalic acid, in 
crystals, to be 7.875, containing three atoms 
of water associated with the two atoms of 
carbon and three of oxygen, which alone en- 
ter into the above combination with oxide of 
lead, and which weigh 4.5. 



Dr Prout's results (Phil. Trans. 1827) 
agree with the above. 

Oxalic acid acts as a violent poison when 
swallowed in the quantity of two or three 
drachms; and several fatal accidents have 
lately occurred in London, in consequence of 
its being improperly sold instead of Epsom 
salts. Its vulgar name of salts, under which 
the acid is bought for the purpose of whiten- 
ing boot-tops, occasions these lamentable mis- 
takes. But the powerfully acid taste of the 
latter substance, joined to its prismatic or 
needle-formed crystallization, are sufficient to 
distinguish it from every thing else. The 
immediate rejection from the stomach of this 
acid by an emetic, aided by copious draughts 
of warm water containing bicarbonate of 
potash, or soda, chalk, or carbonate of mag- 
nesia, are the proper remedies. 

With baryta it forms an insoluble salt; 
but this salt will dissolve in water acidulated 
with oxalic acid, and afford angular crystals. 
If, however, we attempt to dissolve these 
crystals in boiling water, the excess of acid 
will unite with the water, and leave the oxa- 
late, which will be precipitated. 

The oxalate of strontia, too, is a nearly 
soluble compound. 

Oxakte of magnesia, too, is insoluble, un- 
less the acid be in excess. 

The oxalate of potash exists in two states, 
that of a neutral salt, and that of an acidule. 
The latter is generally obtained from the juice 
of the leaves of the oxalis acetosella, wood 
sorrel, or rumex acetosa, common sorrel. The 
expressed juice, being diluted with water, 
should be set by for a few days, till the fecu- 
lent parts have subsided, and the superna- 
tant fluid is become clear ; or it may be cla- 
rified, when expressed, with the whites of 
eggs. It is then to be strained off, evapo- 
rated to a pellicle, and set in a cool place to 
crystallize. The first product of crystals be- 
ing taken out, the liquor may be further eva- 
porated and crystallized, and the same pro- 
cess repeated till no more can be obtained. 
In this way, Schlereth informs us, about nine 
drachms of crystals may be obtained from 
two pounds of juice, which are generally af- 
forded by ten pounds of wood sorrel. Sa- 
vary however says, that ten parts of wood 
sorrel in full vegetation yield five parts of 
juice, which give little more than a two-hun- 
dredth of tolerably pure salt. He boiled 
down the juice, however, in the first instance, 
without clarifying it ; and was obliged re- 
peatedly to dissolve and recrystallize the salt 
to obtain it white. 

This salt is in small, white, needlev, or la- 
mellar crystals, not alterable in the air. It 
unites with baryta, magnesia, soda, ammonia, 
and most of the metallic oxides, into triple 
salts. Yet its solution precipitates the nitric 
solutions of mercury and silver in the state 



ACID 



84 



PHOSPHATIC. 



of insoluble oxalates of these metals, the 
nitric acid in this case combining with the 
potash. It attacks iron, lead, tin, zinc, and 
antimony. 

This salt, besides its use in taking out ink 
spots, and as a test of lime, forms with sugar 
and water a pleasant cooling beverage ; and, 
according to Berthollet, it possesses consider- 
able powers as an antiseptic. 

The neutral oxalate of potash is very so- 
luble, and assumes a gelatinous form, but 
may be brought to crystallize in hexaedral 
prisms with diedral summits, by adding more 
potash to the liquor than is sufficient to sa- 
turate the acid. See SALTS (TABLE OF). 

Oxalate of soda likewise exists in two dif- 
ferent states, those of an acidulous and a 
neutral salt, which, in their properties, are 
analogous to those of potash. 

If oxalic acid be saturated with ammonia, 
we obtain a neutral oxalate, which, on eva- 
poration, yields very fine crystals in tetra'e- 
dral prisms with diedral summits, one of the 
planes of which cuts off three sides of the 
prism. This salt is decomposable by fire, 
which raises from it carbonate of ammonia, 
and leaves only some slight traces of a coaly 
residuum. Lime, baryta and strontia, unite 
with its acid, and the ammonia flies off in 
the form of gas. Its constituents are, acid 
4.5, ammonia 2.125, water 2.25, = 8.875. 

The oxalic acid readily dissolves alumina, 
and the solution gives on evaporation a yellow- 
ish transparent mass, sweet, and a little astrin- 
gent to the taste, deliquescent, and reddening 
tincture of litmus, but not syrup of violets. 
This salt swells up in the fire, loses its acid, 
and leaves the alumina a little coloured. 

The composition of the different oxalates 
may be ascertained by considering the neutral 
salts as consisting of one prime of acid = 4.5 
to one of base, and the binoxylate of potash 
of 2 of acid to one of base, as was first proved 
by Dr Wollaston. But this eminent philo- 
sopher has further shewn, that oxalic acid is 
capable of combining in four proportions with 
the oxides, whence result neutral oxalates, 
suboxalates, acidulous oxalates, and acid ox- 
alates. The neutral contain twice as much 
acid as the suboxalates ; one-half of the quan- 
tity of acid in the acidulous oxalates ; and 
one-quarter of that in the acid oxalates. See 
SALT. 

ACID (PECTIC). The name given by 
Braconnot to an acid which he conceives to 
be universally diffused through vegetables, 
and analogous to, if not identical with jelly. 
85 of this acid seem to neutralize 1 5 of pot- 
ash, and afford a compound like gum-arabic. 
Ann. de Chim. et de Phys. xxviii. 173. 

Vauquelin has recently described processes 
by which this substance may be obtained 
pure, and has pointed out several new pro- 
perties. 

A yellow variety of Flanders carrot was 



rasped, pressed, and washed with common 
water, till the latter passed off limpid. Every 
100 parts of the pressed carrot, with 5 parts 
of bicarbonate of potash, were boiled in water 
the usual time, to form a clear fluid, and then 
pressed ; a strong solution of pectate of pot- 
ash was thus formed, which, being decom- 
posed by excess of muriate of lime, gave an 
insoluble pectate of lime. This was washed 
and treated with water acidulated with mu- 
riatic acid, and finally with pure water. The 
pectic acid thus obtained was very pure, and 
far whiter than that obtained by the use of 
the caustic alkali. 

Carbonate of soda, cautiously employed, 
may prove an economic substitute for the 
bicarbonate of potash. 

If an excess of caustic potash be added to 
gelatinous pectic acid in a platina crucible, 
and gradually heated and agitated, the mix- 
ture soon liquefies and becomes brown. So 
soon as by gradual evaporation the whole of 
the water is dissipated, the saline matter, by 
careful management of the heat, becomes 
rapidly white. 

By examination it is then found, that the 
alkali is nearly neutralized, and that, when 
dissolved, nitric acid evolves a little carbonic 
acid, but no pectic acid ; and by further ex- 
amination the potash will be found neutra- 
lized almost entirely by oxalic acid, formed 
at the expense of the pectic acid first added. 
Ann. de Chim. xli. 46. 

ACID (PHOCENIC). The odorous 
principle of the soap of the dolphin oils, ac- 
cording to M. Chevreul. The sp. gr. of 
phocenic acid is 0.932. It is colourless, and 
takes 100 parts of water to dissolve 5.5 of it. 
It is soluble in alcohol in every proportion. 
Its constituents are in volume, 3 of oxygen, 
10 of carbon, and 14 of hydrogen. 100 of 
phocenic acid neutralize 82.77 of baryta, 
forming a salt soluble in its own weight of 
water at 68 F. The disagreeable smell of 
leather dressed with fish oil, is ascribed by 
M. Chevreul to the decomposition of the 
phocenic acid contained in this oil. Ann. 
de Chim. et de Phys. xxiii. 16. 

ACID (PHOSPHATIC). This acid is 
obtained by the slow combustion of cylinders 
of phosphorus in the air. For which purpose 
it is necessary that the air be renewed to sup- 
port the combustion ; that it be humid, other- 
wise the dry coat of phosphatic acid would 
screen the phosphorus from farther action of 
the oxygen ; and that the different cylinders 
of phosphorus be insulated, to prevent the 
heat from becoming too high, which would 
melt or inflame them, so as to produce phos- 
phoric acid. The acid, as it is formed, must be 
collected in a vessel, so as to lose as little of it 
as possible. All these conditions may be thus 
fulfilled : We take a parcel of glass tubes, 
which are drawn out to a point at one end ; 
we introduce into each a cylinder of phos- 



ACID 



85 



PHOSPHORIC. 



phorus a little shorter than the tube ; we dis- 
pose of these tubes alongside of one another, 
to the amount of 30 or 40, in a glass funnel, 
the beak of which passes into a bottle placed 
on a plate covered with water. We then 
cover the bottle and its funnel with a large 
bell-glass, having a small hole in its top, and 
another in its side. 

A film of phosphorus first evaporates, then 
combines with the oxygen and the water of 
the air, giving birth to phosphatic acid, which 
collects in small drops at the end of the glass 
tubes, and falls through the funnel into the 
bottle. A little phosphatic acid is also found 
on the sides of the bell-glass, and in the wa- 
ter of the plate. The process is a very slow 
one. 

The phosphatic acid thus collected is very 
dilute. We reduce it to a viscid consistence, 
by heating it gently ; and better still, by 
putting it, at the ordinary temperature, into a 
capsule over another capsule full of concen- 
trated sulphuric acid, under the receiver of 
an air-pump, from which we exhaust the air. 

The acid thus foi-med is a viscid liquid, 
without colour, having a faint smell of phos- 
phorus, a strong taste, reddening strongly the 
tincture of litmus, and denser than water in 
a proportion not well determined. Every 
thing leads to the belief that this acid would 
be solid, could we deprive it of water. When 
it is heated in a retort, phosphuretted hydrogen 
gas is evolved, and phosphoric acid remains. 
The oxygen and hydrogen of the water concur 
to this transformation. Phosphatic acid has 
no action, either on oxygen gas, or on the at- 
mospheric air at ordinary temperatures. In 
combining with water, a slight degree of heat 
is occasioned. 

From the experiments of M. Thenard this 
acid seems to consist (exclusive of water) 
of 100 phosphorus united to about 110 oxy- 
gen. 

M. Dulong has shewn, that the phosphatic 
acid, in its action on the salifiable bases, is 
transformed into phosphorous and phosphoric 
acids, whence proceed phosphites and phos- 
phates. 

These proportions agree nearly with two 
primes of phosphorus = (2x40 = 8 X 9 of 
oxygen = 9. 

ACID (PHOSPHORIC). Bonesofbeef, 
mutton or veal, being calcined to whiteness in 
an open fire, lose almost half of their weight. 
These must be pounded, and sifted ; or the 
trouble may be spared, by buying the powder 
that is sold to make cupels for the assayers, 
and is, in fact, the powder of burned bones 
ready sifted. To three pounds of the powder 
there may be added about two pounds of con- 
centrated sulphuric acid. Four or five pounds 
of water must be also added to assist the action 
of the acid. The whole may be then left on 
a gentle sand heat for two or three days, 
taking care to supply the loss of water which 



happens by evaporation. A large quantity of 
water must then be added, the whole strained 
through a sieve, and the residual matter, 
which is sulphate of lime, must be edulco- 
rated by repeated affusions of hot water, till 
it passes tasteless. The waters contain phos- 
phoric acid with a little lime ; and by evapo- 
ration, first in glazed earthen, and then in 
glass vessels, (or rather in vessels of platina or 
silver, for the hot acid acts upon glass), afford 
the impure acid in a concentrated state, which, 
by the force of a strong heat in a crucible, 
may be made to acquire the form of a trans- 
parent consistent glass, though, indeed, it is 
usually of a milky opaque appearance. 

For making phosphorus, it is not necessary 
to evaporate the water further than to bring 
it to the consistence of syrup. But when the 
acid is required in a pure state, it is proper 
to add a quantity of carbonate of ammonia, 
which, by double elective attraction, precipi- 
tates the lime that was held in solution by the 
phosphoric acid. The fluid being then eva- 
porated, affords a crystallized ammoniacal salt, 
which may be melted in a silver vessel, as the 
acid acts upon glass or earthen vessels. The 
ammonia is driven off by the heat, and the 
acid acquires the form of a compact glass, as 
transparent as rock-crystal, acid to the taste, 
soluble in water, and deliquescent in the air. 

This acid is commonly pure, but neverthe- 
less may contain a small quantity of soda, 
originally existing in the bones, and not ca- 
pable of being taken away by this process, in- 
genious as it is. The only unequivocal me- 
thod of obtaining a pure acid appears to con- 
sist in first converting it into phosphorus by 
distillation of the materials with charcoal, and 
then converting this again into acid by rapid 
combustion, at a high temperature, either in 
oxygen, or atmospheric air, or some other 
equivalent process. 

Phosphorus may also be converted into 
the acid state by treating it with nitric acid. 
In this operation, a tubulated retort with a 
ground-stopper must be half-filled with nitric 
acid, and a gentle heat applied. A small 
piece of phosphorus being then introduced 
through the tube, will be dissolved with ef- 
fervescence, produced by the escape of a 
large quantity of nitric oxide. The addition 
of phosphorus must be continued until the 
last piece remains undissolved. The fire be- 
ing then raised to drive over the remainder of 
the nitric acid, the phosphoric acid will be 
found in the retort, partly in the concrete 
and partly in the liquid form. 

When phosphorus is burned by a strong 
heat, sufficient to cause it to flame rapidly, it 
is almost perfectly converted into dry acid, 
some of which is thrown up by the force of 
the combustion, and the rest remains upon 
the supporter. 

This substance has also been acidified by 
the direct application of oxygen gas passed 



ACID 



86 



HYPOPHOSPHOROUS. 



through hot water, in which the phosphorus 
was liquefied or fused. 

The general characters of phosphoric acid 
are, 1. It is soluble in water in all propor- 
tions, producing a specific gravity which in- 
creases as the quantity of acid is greater, but 
does not exceed 2.687, which is that of the 
glacial acid. 2. It produces heat when mixed 
with water, though not very considerable. 3. 
It has no smell when pure, and its taste is 
sour, but not corrosive. 4-. When perfectly 
dry, it sublimes in close vessels ; but loses this 
property by the addition of water ; in which 
circumstance it greatly differs from the boracic 
acid, which is fixed when dry, but rises by 
the help of water. 5. When considerably di- 
luted with water, and evaporated, the aqueous 
vapour carries up a small portion of the acid. 
6. With charcoal or inflammable matter, in a 
strong heat, it loses its oxygen, and becomes 
converted into phosphorus. 

Phosphoric acid is difficult of crystallizing. 

Though phosphoric acid is scarcely corro- 
sive, yet, when concentrated, it acts upon oils, 
which it discolours and at length blackens, 
producing heat, and a strong smell like that 
of ether and oil of turpentine ; but does not 
form a true acid soap. It has most effect on 
essential oils, less on drying oils, and least 
of all on fat oils. 

Ordinary phosphoric acid forms with oxide 
of silver a yellow phosphate ; but if the acid 
is previously subjected to ignition, the silver 
compound is white. Mr Clark had previous- 
ly shewn, that common phosphate of soda, 
which precipitates nitrate of silver yellow, is 
changed by heat into what he calls a pyro- 
phosphate, which precipitates nitrate of silver 
white. 

The experiments of Berzelius show it to 
be a compound of about 100 phosphorus -j- 
128 oxygen. M. Dulong, in an elaborate 
paper published in the third volume of the 
Memoires D'Arcueil, gives, as the result of 
diversified experiments, nearly the proportions 
of 100 phosphorus to 123 oxygen ; or of 5 
oxygen -|- 4 phosphorus = 9, for the acid 
equivalent. 

M. Dumas, in an elaborate memoir on Phos- 
phuretted Hydrogen (Annales de Chim. et de 
Phys. xxxi.), endeavours to show that phos- 
phoric acid consists of 1 atom of phosphorus 
4>.0 -J- 5 atoms of oxygen 5= 9; while 
phosphorous acid consists of 1 atom of phos- 
phorus 4 -\- 3 atoms of oxygen 3=7. See 
PHOSPHURETTED HYDROGEN, and General 
Table of GASES. 

If phosphoric acid be made 9, then in the 
phosphates of soda, baryta, and lead, we must 
admit 2 atoms of base ; thus giving them the 
characters of subsalts, which that of soda ma- 
nifestly possesses. 

ACID (PHOSPHOROUS) was disco- 
vered in 1812 by Sir H. Davy. When phos- 
phorus and corrosive sublimate act on each 



other at an elevated temperature, a liquid 
called protochloride of phosphorus is formed. 
Water added to this, resolves it into muriatic 
and phosphorous acids. A moderate heat 
suffices to expel the former, and the latter re- 
mains associated with water. It has a very 
sour taste, reddens vegetable blues, and neu- 
tralizes bases. When heated strongly in open 
vessels, it inflames. Phosphuretted hydrogen 
flies off, and phosphoric acid remains. Ten 
parts of it heated in close vessels, give off one- 
half of a phosphuretted hydrogen, and leave 
83- of phosphoric acid. Hence the liquid 
acid consists of 80.7 acid -f- 19.3 water. See 
PROS. HYDROGEN. 

ACID (HYPOPHOSPHOROUS), late- 
ly discovered by M. Dulong. Pour water 
on the phosphuret of baryta, and wait till all 
the phosphuretted hydrogen be disengaged. 
Add cautiously to the filtered liquid dilute 
sulphuric acid, till the baryta be all precipi- 
tated in the state of sulphate. The superna- 
tant liquid is hypophosphorous acid, which 
should be passed through a filter. This li- 
quid may be concentrated by evaporation, till 
it becomes viscid. It has a very sour taste, 
reddens vegetable blues, and does not crys- 
tallize. Dulong assigns 100 phosphorus to 
37.44 oxygen, which gives the proportion of 
1 atom phosphorus 4.0-j- H oxygen 1.5 = 
5.5 for the acid prime equivalent. The hy- 
pophosphites have the remarkable property of 
being all soluble in water ; while many of 
the phosphates and phosphites are insoluble. 

According to M. Rose, the hypophosphites 
of lime, baryta, and strontia, may be prepar- 
ed by boiling the earths with phosphorus and 
water. In preparing that of lime, the phos- 
phorus should not be added before the milk 
of lime boils ; and the operation should be 
continued till all the phosphorus has disap- 
peared, and the peculiar smell has ceased. 
Carbonic acid is then to be passed through 
to separate the excess of caustic lime, the in- 
soluble parts separated by the filter, and the 
solution evaporated under the air-pump, or 
in close vessels by heat. It then crystallizes 
with more or less water, according to circum- 
stances, those obtained by heat having the 
least. 

The hypophosphites of baryta and strontia 
may be prepared in the same way, and have 
the same general properties. These earthy 
salts are insoluble in alcohol. 

The alkaline hypophosphites may be made 
either directly, or by mixing hypophosphite 
of lime with excess of the alkaline carbonate, 
filtering, evaporating to dryness, and digest- 
ing in alcohol, by which the alkaline hypophos- 
phites are dissolved. The potash salt is the 
most deliquescent salt known to M. Rose; 
the soda salt is less so, crystallizing in rec- 
tangular prisms. 

All the hypophosphites are soluble in wa- 
ter. The hypophosphorous acid was obtain- 



ACID 



HYPOPHOSPHOROUS. 



ed pure, and in quantity, by boiling the hy- 
drate of baryta with water and phosphorus 
till all garlic odour ceased ; filtering the li- 
quid, and decomposing it by sulphuric acid 
in excess ; separating the precipitate, and di- 
gesting the clear fluid for a short time with 
an excess of oxide of lead ; then filtering the 
sulphate of lead from the solution of hypo- 
phosphite, and decomposing the latter by a 
current of sulphuretted hydrogen. The acid 
freed from the sulphuret of lead, may be con- 
centrated until strong enough to form the 
required salts. 

With regard to the phosphates and phos- 
phites, we have many discrepancies in our 
latest publications. Sir H. Davy says, in his 
last memoir on some of the combinations of 
phosphorus, that " new researches are requir- 
ed to explain the anomalies presented by the 
phosphates." 

Phosphoric acid, united with baryta, pro- 
duces an insoluble salt, in the form of a heavy 
white powder, fusible at a high temperature 
into a grey enamel. The best mode of pre- 
paring it is, by adding an alkaline phosphate 
to the nitrate or muriate of baryta. 

By mixing phosphate of ammonia with 
nitrate of baryta, Berzelius found that 68.2 
parts of baryta and 31.8 of phosphorus com- 
posed 100 of the phosphate. Hence it is a 
subphosphate, and consists of, 

Phosphoric acid 1 atom =9.0 68.42 

Baryta 2 == 19.5 31.58 

100.0 

He made a phosphate by dissolving the above 
in dilute phosphoric acid, and evaporating, 
when crystals were obtained composed, in 100 
parts, of acid 42.54, baryta 46.46, water 11. 
But by theory we have, 

Acid, 2 atoms 18 42.857) 
Base, 2 19.5 46.430 C 100.000 

Water, 4 4.5 10.713) 

By pouring a solution of the preceding salt 
into alcohol, a sesquiphosphate is obtained, in 
the form of a light white powder, containing 
H times as much acid as the subphosphate. 
The phosphate of strontia differs from the 
preceding, in being soluble in an excess of its 
acid. 

Phosphate of lime is very abundant in the 
native state. See APATITE. It likewise con- 
stitutes the chief part of the bones of all ani- 
mals. 

Phosphate of lime is very difficult to fuse, 
but in a glasshouse furnace it softens, and 
acquires the semitransparency and grain of 
porcelain. It is insoluble in water, but when 
well calcined, forms a kind of paste with it, as 
in making cupels. Besides this use of it, it 
is employed for polishing gems and metals, 
for absorbing grease from cloth, linen, or pa- 
per, and for preparing phosphorus. In me- 
dicine it has been strongly recommended 
against the rickets by Dr Bonhomme of 



Avignon, either alone or combined with phos- 
phate of soda. The burnt hartshorn of the 
shops is a phosphate of lime. 

An acidulous phosphate of lime is found in 
human urine, and may be crystallized in small 
silky filaments, or shining scales, which unite 
together into something like the consistence of 
honey, and have a perceptibly acid taste. It 
may be prepared by partially decomposing the 
calcareous phosphate of bones by the sulphu- 
ric, nitric, or muriatic acid, or by dissolving 
that phosphate in phosphoric acid. It is so- 
luble in water, and crystallizable. Exposed 
to the action of heat, it softens, liquefies, 
swells up, becomes dry, and may be fused 
into a transparent glass, which is insipid, in- 
soluble, and unalterable in the air. In these 
characters it differs from the glacial acid of 
phosphorus. It is partly decomposable by 
charcoal, so as to afford phosphorus. 

By pouring phosphate of soda into mu- 
riate of lime, Berzelius obtained a phosphate 
of lime, consisting of acid 100, lime 84.53. 
The theoretic proportions are, 
Phosphoric acid = 9 = 100 
Lime 3.5 X 2 = 7 = 78 nearly. 

Phosphate of potash is very deliquescent, 
and not crystallizable, but condensing into a 
kind of jelly. Like the preceding species, 
it first undergoes the aqueous fusion, swells, 
dries, and may be fused into a glass ; but this 
glass deliquesces. It has a sweetish saline 
taste. Phosphate of soda is now commonly 
prepared by adding to the acidulous phosphate 
of lime as much carbonate of soda in solution 
as will fully saturate the acid. The carbonate 
of lime which precipitates being separated by 
filtration, the liquid is duly evaporated so as 
to crystallize the phosphate of soda ; but if 
there be not a slight excess of alkali, the crys- 
tals will not be large and regular. The crys- 
tals are rhomboidal prisms of different shapes, 
efflorescent, soluble in three parts of cold and 
H of hot water. They are capable of being 
fused into an opaque white glass, which may 
be again dissolved and crystallized. It may 
be converted into an acidulous phosphate by 
an addition of acid, or by either of the strong 
acids, which partially, but not wholly, de- 
compose it. As its taste is simply saline, 
without any thing disagreeable, it is much 
used as a purgative, chiefly in broth, in which 
it is not distinguishable from common salt. 
For this elegant addition to our pharmaceu- 
tical preparations, we are indebted to Dr 
Pearson. In assays with the blowpipe it is 
of great utility ; and it has been used instead 
of borax for soldering. 

In crystals, this salt is composed, according 
to Berzelius, of phosphoric acid 20.33, soda 
17.67, water 62.00; and in the dry state, of 
acid 53.48, soda 46.52. If it be represented 
by 1 atom of acid = 9 -{- 2 atoms soda = 8, 
then 100 of the dry salt will consist of acid 53, 
base 47 ; and, in the crystallized state, of 



ACID 



88 



PURPURIC. 



Water, 24 atoms 27 61.4 
Acid, 1 9 20.4 

Soda, 2 8 18.2 

100.0 

which presents a good accordance with the 
experimental results of Berzelius. 

I must here notice the curious observations 
of Mr Thomas Clark on this salt. He finds, 
that when phosphate of soda is ignited, it ac- 
quires peculiar properties, though its compo- 
sition is unchanged. It then precipitates 
nitrate of silver from its watery solution, not 
yellow, but white ; and furnishes a superna- 
tant liquid, not acidulous, as with the com- 
mon phosphate, but neutral To this modi- 
fication of the salt he gives the name of pyro- 
phosphate of soda. He considers the phos- 
phate of soda to contain, in its crystallized 
state, 25 atoms of water ; of which 24* are 
separable by a sand bath heat, and the 25th 
by a red heat. In losing this one proportion 
of water, phosphate of soda becomes pyro- 
phosphate. He finds arseniate of soda to 
resemble it in containing 25 prime propor- 
tions of water, the last one of which is sepa- 
rable only at a red heat. This is in accord- 
ance with M. Mitscherlich's views of the 
isomorphism and analogous constitution of 
the arseniates and phosphates. The arseniates 
of soda, however, acquire no new property 
by ignition. 

The phosphate of ammonia crystallizes in 
prisms with four regular sides, terminating 
in pyramids, and sometimes in bundles of 
small needles. Its taste is cool, saline, pun- 
gent, and urinous. On the fire it comports 
itself like the preceding species, except that 
the whole of its base may be driven off by a 
continuance of the heat, leaving only the acid 
behind. It is but little more soluble in hot 
water than in cold, which takes up a fourth 
oC its weight. It is pretty abundant in hu- 
man urine. It is an excellent flux both for 
assays and the blowpipe, and in the fabrica- 
tion of coloured glass and artificial gems. 

Phosphate of magnesia crystallizes in irre- 
gular hexaedral prisms, obliquely truncated; 
but is commonly pulverulent, as it effloresces 
very quickly. It requires fifty parts of water 
to dissolve it. Its taste is cool and sweetish. 
This salt too is found in urine. Fourcroy and 
Vauquelin have discovered it likewise in small 
quantity in the bones of various animals, 
though not in those of man. The best way of 
preparing it is by mixing equal parts of the 
solutions of phosphate of soda and sulphate of 
magnesia, and leaving them some time at rest, 
when the phosphate of magnesia will crystal- 
lize, and leave the sulphate of soda dissolved. 

An ammonia-magnesian phosphate has been 
discovered in an intestinal calculus of a horse 
by Fourcroy, and since by Bartholdi, and like- 
wise by the former in some human urinary 
calculi. See CALCULUS. Notwithstanding 



the solubility of the phosphate of ammonia, 
this triple salt is far less soluble than the phos- 
phate of magnesia. It is partially decompo- 
sable into phosphorus by charcoal, in conse- 
quence of its ammonia. 

The phosphate of glucina has been examin- 
ed by Vauquelin, who informs us, that it is a 
white powder, or mucilaginous mass, without 
any perceptible taste ; fusible, but not decom- 
posable by heat ; unalterable in the air, and 
insoluble unless in an excess of its acid. 

It has been observed, that the phosphoric 
acid, aided by heat, acts upon silex ; and we 
may add, that it enters into many artificial 
gems in the state of a siliceous phosphate. 
See SALT. 

ACID (PINIC). In the colophony of 
France (rosin), derived in all probability from 
the pinus maritima or pinaster, M. Baup has 
found a substance which crystallizes in trian- 
gular plates, soluble in about four parts of 
alcohol, but insoluble in water. It reacts like 
an acid, and neutralizes alkaline matter. He 
calls it Pinic acid. Annales de Chim. et 
de Phys. xxxi. 

Pinic acid has been found, by M. Unver- 
dorben, to be a constituent of Venice turpen- 
tine. 

When Venice turpentine has been distilled 
with 20 parts of water, till half the water has 
passed over, and this operation has been re- 
peated several times, a semi- viscid mixture of 
resin with oils is left in the retort. This dis- 
solved in alcohol of 65 per cent, gives a green 
precipitate, with an alcoholic solution of ace- 
tate of copper. This precipitate is pinate of 
copper, which being washed on a filter with 
alcohol, and then dissolved in alcohol with a 
little muriatic acid, may have the pinic acid 
precipitated by water, as a white, resinous, 
and transparent substance. Being then 
washed with boiling water, the alcohol is re- 
moved, and it becomes a solid, inodorous, 
and almost insipid body. 

The pinates of potash and soda are obtain- 
ed by slowly boiling an ethereal solution of 
pinic acid, for a few minutes, with the alka- 
line carbonates, filtering and evaporating the 
solutions ; the residuum is the alkaline pinate, 
a resinous, colourless mass, which dissolves 
completely in boiling water. The pinate of 
potash is precipitated from its concentrated 
solution, not only by an excess of potash or 
soda, but also by neutral salts, as sulphate of 
soda, muriate of soda, acetate of potash, &c. 

The pinates of baryta, alumina, man- 
ganese, and zinc, are insoluble in alcohol, 
very soluble in ether, and resemble earthy 
bodies. 

According to M. Unverdorben, the pinic 
acid should be placed immediately after the 
benzoic. 

ACID (PURPURIC). The excrements 
of the serpent Boa constrictor consist of pure 
lithic acid, Dr Prout found, that on digest- 



ACID 



89 



PYROCITRIC. 



ing this substance thus obtained, or from uri- 
nary calculi, in dilute nitric acid, an effer- 
vescence takes place, and the lithic acid is 
dissolved, forming a beautiful purple liquid. 
The excess of nitric acid being neutralized 
with ammonia, and the whole concentrated 
by slow evaporation, the colour of the solu- 
tion becomes of a deeper purple ; and dark 
red granular crystals, sometimes of a green- 
ish hue externally, soon begin to separate in 
abundance. These crystals are a compound 
of ammonia with the acid principle in ques- 
tion. The ammonia was displaced by digest- 
ing the salt in a solution of caustic potash, 
till the red colour entirely disappeared. This 
alkaline solution was then gradually dropped 
into dilute sulphuric acid, which, uniting with 
the potash, left the acid principle in a state of 
purity. 

This acid principle is likewise produced 
from lithic acid by chlorine, and also, but 
with more difficulty, by iodine. Dr Prout, 
the discoverer of this new acid, has, at the 
suggestion of Dr Wollaston, called it pur- 
puric acid, because its saline compounds have 
for the most part a red or purple colour. 

This acid, as obtained by the preceding 
process, usually exists in the form of a very 
tine powder, of a slightly yellowish or cream 
colour ; and when examined with a magnifier, 
especially under water, appears to possess a 
pearly lustre. It has no smell, nor taste. Its 
sp. grav. is considerably above water. It is 
scarcely soluble in water. One-tenth of a 
grain, boiled for a considerable time in 1000 
grains of water, was not entirely dissolved. 
The water, however, assumed a purple tint, 
probably, Dr Prout thinks, from the forma- 
tion of a little purpurate of ammonia. Pur- 
puric acid is insoluble in alcohol and ether. 
The mineral acids dissolve it only when they 
are concentrated. It does not affect litmus 
paper. By igniting it in contact with oxide 
of copper, he determined its composition to be, 
2 atoms hydrogen, 0.250 - 4.54 
2 carbon, 1.500 - 27.27 

2 oxygen, 2.000 - 36.36 

1 azote, 1.750 - 31.81 

5.50 99.98 

Purpuric acid combines with the alkalis, al- 
kaline earths, and metallic oxides. It is ca- 
pable of expelling carbonic acid from the 
alkaline carbonates by the assistance of heat, 
and does not combine with any other acid. 
These are circumstances sufficient, as Dr 
Wollaston observed, to distinguish it from 
an oxide, and to establish its character as an 
acid. 

Purpurate of ammonia crystallizes in qua- 
drangular prisms, of a deep garnet-red colour. 
It is soluble in 1500 parts of water at 60, and 
in much less at the boiling temperature. The 
solution is of a beautiful deep carmine, or rose- 
red colour. It has a slightly sweetish taste, 



but no smell. Purpurate of potash is much 
more soluble ; that of soda is less ; that of 
lime is nearly insoluble; those of strontia 
and lime are slightly soluble. All the solu- 
tions have the characteristic colour. Pur- 
purate of magnesia is very soluble ; and in 
solution, of a very beautiful colour. A so- 
lution of acetate of zinc produces, with pur- 
purate of ammonia, a solution and precipitate 
of a beautiful gold-yellow colour ; and a most 
brilliant iridescent pellicle, in which green and 
yellow predominate, forms on the surface of 
the solution. Dr Prout conceives the salts 
to be anhydrous, or void of water, and com- 
posed of two atoms of acid and one of base. 
The purpuric acid and its compounds pro- 
bably constitute the bases of many animal 
and vegetable colours. The well known pink 
sediment which generally appears in the urine 
of those labouring under febrile affections, 
appears to owe its colour chiefly to the pur- 
purate of ammonia, and perhaps occasionally 
to the purpurate of soda. 

The solution of lithic acid in nitric acid 
stains the skin of a permanent colour, which 
becomes of a deep purple on exposure to the 
sun. These apparently sound experimental 
deductions of Dr Prout have been called in 
question by M. Vauquelin ; but Dr Prout 
ascribes M. Vauquelin's failure in attempt- 
ing to procure purpuric acid, to his having 
operated on an impure lithic acid. I think 
entire confidence may be put in Dr Prout's 
experiments. He says that it is difficult to 
obtain purpuric acid from the lithic acid of 
urinary concretions. Phil. Trans, for 1818, 
and Annals of Phil. vol. xiv. 

ACID (PYROCITRIC). When citric 
acid is put to distil in a retort, it begins at 
first by melting ; the water of crystallization 
separates almost entirely from it by a continu- 
ance of the fusion ; then it assumes a yellow- 
ish tint, which gradually deepens. At the 
same time there is disengaged a white vapour, 
which goes over to be condensed in the re- 
ceiver. Towards the end of the calcination 
a brownish vapour is seen to form, and there 
remains in the bottom of the retort a light 
very brilliant charcoal. 

The product contained in the receiver con- 
sists of two different liquids. One, of an 
amber-yellow colour, and an oily aspect, oc- 
cupies the lower part; another, colourless 
and liquid like water, of a very decided acid 
taste, floats above. After separating them 
from one another, we perceive that the first 
has a very strong bituminous odour, and an 
acid and acrid taste ; that it reddens power- 
fully the tincture of litmus, but that it may 
be deprived almost entirely of that acidity by 
agitation with water, in which it divides itself 
into globules, which soon fall to the bottom 
of the vessel, and are not long in uniting into 
one mass, in the manner of oils heavier than 
water. 



ACJD 



90 



PYROCITRIC. 



In this state it possesses some of the pro- 
perties of these substances ; it is soluble in 
alcohol, ether, and the caustic alkalis. How- 
ever, it does not long continue thus ; it be- 
comes acid, and sometimes even it is observ- 
ed to deposit, at the end of some days, white 
crystals, which have a very strong acidity : if 
we then agitate it anew with water, it dis- 
solves in a great measure, and abandons a 
yellow or brownish pitchy matter, of a very 
obvious empyreumatic smell, and which has 
much analogy with the oil obtained in the 
distillation of other vegetable matters. The 
same effect takes place when we keep it under 
water ; it diminishes gradually in volume, the 
water acquires a sour taste, and a thick oil 
remains at the bottom of the vessel. 

This liquid may be regarded as a combi- 
nation (of little permanence indeed) of the 
peculiar acid which the oil formed in similar 
circumstances. 

As to the liquid and colourless portion 
which floated over this oil, it was ascertained 
to contain no citric acid carried over, nor 
acetic acid ; first, because on saturating it 
with carbonate of lime, a soluble calcareous 
salt was obtained ; and, secondly, because this 
salt, treated with sulphuric acid, evolved no 
odour of acetic acid. 

From this calcareous salt the lime was se- 
parated by oxalic acid ; or the salt itself was 
decomposed with acetate of lead, and the pre- 
cipitate treated with sulphuretted hydrogen. 
By these two processes, this new acid was 
separated in a state of purity. 

Properties of the pyrocitric acid. This 
acid is white, inodorous, of a strongly acid 
taste. It is difficult to make it crystallize in 
a regular manner, but it is usually presented 
in a white mass, formed by the interlacement 
of very fine small needles. Projected on a 
hot body it melts, is converted into white very 
pungent vapours, and leaves some traces of 
carbon. When heated in a retort, it affords 
an oily-looking acid, and yellowish liquid, 
and is partially decomposed. It is very solu- 
ble in water and in alcohol; water at the 
temperature of 10 C. (50 F.) dissolves one- 
third of its weight. The watery solution has 
a strongly acid taste ; it does not precipitate 
lime or baryta water, nor the greater part of 
metallic solutions, with the exception of ace- 
tate of lead and protonitrate of mercury. With 
the oxides it forms salts possessing properties 
different from the citrates. 

The pyrocitrate of potash crystallizes in 
small needles, which are white, and unalter- 
able in the air. It dissolves in about 4 parts 
of water. Its solution gives no precipitate 
with the nitrate of silver or of baryta ; whilst 
that of the citrate of baryta forms precipitates 
with these salts. 

The pyrocitrate of lime directly formed, ex- 
hibits a white crystalline mass, composed of 
needles opposed to each other, in a ramifica- 



tion form. This salt has a sharp taste. It 
dissolves in 25 parts of water at 50 Fahr. 
It contains 30 per cent of water of crystalli- 
zation, and is composed, in its dry state, of 
Pyrocitric acid, 34* 

Lime, 66 

The solution of the pyrocitric acid satura- 
ted with baryta water, lets fall, at the end of 
some hours, a very white crystalline powder, 
which is pyrocitrate of baryta. This salt is 
soluble in 150 parts of cold water, and in 50 
of boiling water. Two grammes of this salt, 
decomposed by sulphuric acid, furnished 1.7 
of sulphate of baryta, which gives for its com- 
position, 

Pyrocitric aciti, 43.9 
Baryta, 56. 1 

The pyrocitrate of lead is easily obtained 
by pouring pyrocitrate of potash into a solu- 
tion of acetate of lead. The pyrocitrate of 
lead presents itself under the form of a white 
gelatinous semitransparent mass, which be- 
comes dry in the air, shrinking like gelatinous 
alumina, to which, in its physical characters, 
it has much analogy. It contains 8 per cent 
of water, and is formed of 

Pyrocitric acid, 33.4 
Protoxide of lead, 66.6 
Knowing the composition of pyrocitrate of 
lead, it was employed, by ignition with oxide 
of copper, to determine that of the acid itself^ 
which is stated as being 

Carbon, 47.5 

Oxygen, 43.5 

Hydrogen, 9.0 

100.0 

The proportion of the elements of this acid 
is very different then from that which MM. 
Gay Lussac, Thenard, and Berzelius, have 
found for citric acid. " But what is remark- 
able," says M. Lassaigne, " its capacity for 
saturation is nearly the same as that of citric 
acid, as we may see by casting our eyes on the 
analyses of the pyrocitrates of lime, baryta, 
and lead, which we have given, and which we 
have convinced ourselves of by frequent veri- 
fication. Nevertheless, in the combination of 
this new acid, the ratio of the oxygen of the 
oxide to the oxygen of the acid is in a dif- 
ferent proportion from that admitted for the 
neutral citrates : we observe, that in the py- 
rocitrates the oxygen of the base is to that of 
the acid as I to 3.07 ; whilst in the citrates 
it is as 1 to 4.916." 

The author seems here to have miscalcu- 
lated strangely. Taking his analysis of pyro- 
citrate of lime and of pyrocitric acid, we have 
34 acid, which contain 14.6 of oxygen, 
66 lime, 18.6 of oxygen ; 

so that the oxygen of the base is to that of 
the acid as 1 to 0.785, instead of 1 to 3.07. 
In fact, the pyrocitrate of lime result 
makes the atom of acid, referred to Dr Wol- 
laston's scale, to be 18.3; that for pyroci- 



ACID 



91 



PYROLITHIC. 



trate of baryta makes it 76.5, and that for 
pyrocitrate of lead, 70. The only supposi- 
tion we can form is, that the numbers for 
the calcareous salt are inverted in the Jour- 
nal de Pharmacie ; and that they ought to be, 
Pyrocitric acid, 66 

T CM 

.Lime, o* 

In this case the atom comes out 69.0; a 
tolerable accordance with the above. Were 
the equivalent of the acid 66.25, then it 
might consist of 

Carbon, 4 atoms = 30.00 45.27 
Oxygen, 3 - = 30.00 45.27 
Hydrogen, 5 - =6.25 9.46 

66.25 100.00 

ACID (PYROLIGNOUS). In the 
destructive distillation of any kind of wood 
an acid is obtained, which was formerly 
called acid spirit of wood, and since, pyrolig- 
nous acid. Fourcroy and Vauquelin show- 
ed that this acid was merely the acetic, con- 
taminated with empyreumatic oil and bitu- 
men. See ACID ( ACETIC). 

Under acetic acid will be found a full ac- 
count of the production and purification of 
pyrolignous acid. M. Monge discovered, 
about five years ago, that this acid has the 
property of preventing the decomposition of 
animal substances. But I have lately learn- 
ed, that Mr William Dinsdale, of Field Cot- 
tage, Colchester, three years prior to the date 
of M. Monge's discovery, did propose to the 
Lords Commissioners of the Admiralty, to 
apply a pyrolignous acid, (prepared out of 
the contact of iron vessels, which blacken it), 
to the purpose of preserving animal food, 
wherever their ships might go. As this 
application may in many cases afford valu- 
able antiscorbutic articles of food, and thence 
be eminently conducive to the health of sea- 
men, it is to be hoped that their Lordships 
will, ere long, carry into effect Mr Dinsdale's 
ingenious plan, as far as shall be deemed 
necessary. It is sufficient to plunge meat 
for a few moments into this acid, even 
slightly empyreumatic, to preserve it as long 
as you please. " Putrefaction," it is said, 
" not only stops, but retrogrades." To the 
empyreumatic oil a part of this effect has 
been ascribed ; and hence has been accounted 
for, the agency of smoke in the preservation 
of tongues, hams, herrings, &c. Dr Jorg of 
Leipsic has entirely recovered several ana- 
tomical preparations from incipient corrup- 
tion by pouring this acid over them. With 
the empyreumatic oil or tar he has smeared 
pieces of flesh already advanced in decay, 
and notwithstanding that the weather was 
hot, they soon became dry and sound. To 
the above statements Mr Ramsay of Glas- 
gow, an eminent manufacturer of pyrolig- 
nous acid, and well known for the purity of 
his vinegar from wood, has recently added 
the following facts in the 5th number of the 



Edinburgh Philosophical Journal. If fish be 
simply dipped in redistilled pyrolignous acid, 
of the specific gravity 1.012, and afterwards 
dried in the shade, they preserve perfectly 
well. On boiling herrings treated in this 
manner, they were very agreeable to the 
taste, and had nothing of the disagreeable 
empyreuma which those of his earlier expe- 
riments had, which were steeped for three 
hours in the acid. A number of very fine 
haddocks were cleaned, split, and slightly 
sprinkled with salt for six hours. After 
being drained, they were dipped for about 
three seconds in pyrolignous acid, then hung 
up in the shade for six days. On being 
broiled, the fish were of an uncommonly fine 
flavour, and delicately white. Beef treated 
in the same way had the same flavour as 
Hamburgh beef, and kept as well. Mr 
Ramsay has since found, that his perfectly 
purified vinegar, specific gravity 1.034, being 
applied by a cloth or sponge to the surface of 
fresh meat, makes it keep sweet and sound 
for several days longer in summer than it 
otherwise would. Immersion for a minute 
in his purified common vinegar, specific gra- 
vity 1.009, protects beef and fish from all 
taint in summer, provided they be hung up 
and dried in the shade. When, by frequent 
use, the pyrolignous acid has become impure, 
it may be clarified by beating up twenty 
gallons of it with a dozen of eggs in the 
usual manner, and heating the mixture in 
an iron boiler. Before boiling, the eggs 
coagulate, and bring the impurities to the 
surface of the boiler, which are of course to 
be carefully skimmed off. This acid must 
be immediately withdrawn from the boiler, 
as it acts on iron. 

ACID (PYROLITHIC). When uric 
acid concretions are distilled in a retort, sil- 
very white plates sublime. These are pyro- 
lithate of ammonia. When their solution is 
poured into that of subacetate of lead, a py- 
rolithate of lead falls, which, after proper 
washing, is to be shaken with water, and de- 
composed by sulphuretted hydrogen gas. 
The supernatant liquid is now a solution of 
pyrolithic acid, which yields small acicular 
crystals by evaporation. By heat these melt, 
and sublime in white needles. They are 
soluble in four parts of cold water, and the 
solution reddens vegetable blues. Boiling 
alcohol dissolves the acid, but on cooling it 
deposits it, in small white grains. Nitric 
acid dissolves without changing it. Hence, 
pyrolithic is a different acid from the lithic, 
which, by nitric acid, is convertible into pur- 
purate of ammonia. The pyrolithate of lime 
crystallizes in stalactites, which have a bitter 
and slightly acrid taste. It consists of 91.4 
acid -}- 8.6 lime. Pyrolithate of baryta is a 
nearly insoluble powder. The salts of pot- 
ash, soda, and ammonia, are soluble, and the 
former two cry stall izable. At a red heat, 



ACID 



PYROMUCIC. 



and by passing it over ignited oxide of cop- 
per, it is decomposed, into oxygen 44.32, 
carbon 28.29, azote 16.84, hydrogen 10. 

ACID (PYROMALIC). When malic 
or sorbic acid, for they are the same, is dis- 
tilled in a retort, an acid sublimate, in white 
needles, appears in the neck of the retort, 
and an acid liquid distils into the receiver. 
This liquid, by evaporation, affords crystals, 
constituting a peculiar acid, to which the 
above name has been given. 

They are permanent in the air, melt at 
118 Fahr., and on cooling form a pearl- 
coloured mass of diverging needles. When 
thrown on red-hot coals, they completely 
evaporate in an acrid cough-exciting smoke. 
Exposed to a strong heat in a retort, they are 
partly sublimed in needles, and are partly de- 
composed. They are very soluble in strong 
alcohol, and in double their weight of water, 
at the ordinary temperature. The solution 
reddens vegetable blues, and yields white 
flocculent precipitates with acetate of lead 
and nitrate of mercury; but produces no 
precipitate with lime water. By mixing it 
with baryta water, a white powder falls, 
which is redissolved by dilution with water; 
after which, by gentle evaporation, the pyro- 
malate of baryta may be obtained in silvery 
plates. These consist of 100 acid, and 
185.142 baryta, or in prime equivalents, of 
5.25 -f 9.75. 

Pyromalate of potash may be obtained in 
feather-formed crystals, which deliquesce. 
Pyromalate of lead forms first a white floc- 
culent precipitate, soon passing into a semi- 
transparent jelly, which, by dilution and fil- 
tration from the water, yields brilliant pearly- 
looking needles. The white crystals that 
sublime in the original distillation, are con- 
sidered by M. Lassaigne as a peculiar acid. 

ACID (PYROMUCIC). This acid, 
discovered in 1818 by M. Houton Labillar- 
diere, is one of the products of the distillation 
of mucic acid. When we wish to procure it, 
the operation must be performed in a glass 
retort furnished with a receiver. The acid 
is formed in the brown liquid which is pro- 
duced along with it, and which contains 
water, acetic acid, and empyreumatic oil ; a 
very small quantky of the pyromucic acid 
remaining attached to the vault of the retort, 
under the form of crystals. These crystals 
being coloured are added to the brown liquor, 
which is then diluted with three or four times 
its quantity of water, in order to throw down 
a certain portion of oil. The whole is next 
filtered, and evaporated to a suitable degree. 
A great deal of acetic acid is volatilized, and 
then the new acid crystallizes. On decant- 
ing the mother waters, and concentrating 
them farther, they yield crystals anew ; but 
as these are small and yellowish, it is neces- 
sary to make them undergo a second distilla- 
tion, to render them susceptible of being per- 



fectly purified by crystallization. 150 parts 
of mucic acid furnish about 60 of brown 
liquor, from which we can obtain eight to ten 
of pure pyromucic acid. 

This acid is white, inodorous, of a strongly 
acid taste, and a decided action on litmus. 
Exposed to heat in a retort it melts at the 
temperature of 266 F., then volatilizes, and 
condenses into a liquid, which passes on cool- 
ing into a crystalline mass, covered with very 
fine needles. It leaves very slight traces of 
residuum in the bottom of the retort. 

On burning coals, it instantly diffuses 
white pungent vapours. Air has no action 
on it. Water at 60 dissolves l-28th of its 
weight. Boiling water dissolves it much 
more abundantly, and on cooling abandons 
a portion of it, in small elongated plates, 
which cross in every direction. 

Subacetate of lead is the only salt of whose 
oxide it throws down a portion. 

It consists in 100 parts of 

Carbon, 52.118 

Oxygen, 45.806 

Hydrogen, 2.111 

This acid unites readily to the salifiable 
bases, and forms , 

With potash, a salt very soluble in water 
and alcohol, deliquescent, and which, evapo- 
rated to a pellicle, congeals into a granular 
mass; 

With soda, a salt less deliquescent and less 
soluble in water and alcohol than the pre- 
ceding, but which crystallizes with difficul- 
ty; 

With baryta, strontia, and lime, salts 
soluble in water, and a little more so in hot 
than in cold, insoluble in alcohol, and easily 
obtained in crystals, which are permanent in 
the air ; 

With ammonia, a salt soluble in water, 
which, by evaporation of the liquid, loses a 
portion of its base, becomes acid, and then 
crystallizes with facility; 

With protoxide of lec^, a neutral soluble 
salt, which possesses remarkable properties. 
This salt is obtained by putting liquid pyro- 
mucic acid in contact with moist carbonate 
of lead. When we evaporate the solution, 
the salt collects at the surface in transparent 
liquid globules, of a brownish colour and an 
oily aspect ; which, a little after they are re- 
moved, assume the softness and toughness of 
pitch, and finally become solid, opaque, and 
whitish. This property belongs also to suc- 
cinate of lead. 

The alkaline pyromucates occasion scarcely 
any turbidity in the solutions of the metallic 
salts, if we except those of the peroxide of 
iron, of the peroxide of mercury, the subace- 
tate of lead, and the protonitrate of tin. The 
deposit formed in the salts of iron is a yellow 
similar to that of turbeth mineral. 

In all the salts in the neutral state, the 
quantity of oxygen in the oxide is to the 



ACID 



93 



SEBACIC. 



quantity in the acid as one to thirteen, which 
number therefore represents the equivalent 
weight of pyromucic acid. Ann. de Chim. 
et de Phys. ix. 365. 

ACID (PYROTARTARIC). Into a 
coated glass retort introduce tartar, or rather 
tartaric acid, till it is half full, and fit to it a 
tubulated receiver. Apply heat, which is to 
be gradually raised to redness. Pyrotartaric 
acid of a brown colour, from impurity, is 
found in the liquid products. We must filter 
these through paper previously wetted, to se- 
parate the oily matter. Saturate the liquid 
with carbonate of potash ; evaporate to dry- 
ness ; redissolve, and filter through clean 
moistened paper. By repeating this process 
of evaporation, solution, and filtration, seve- 
ral times, we succeed in separating all the 
oil. The dry salt is then to be treated in a 
glass retort, at a moderate heat, with dilute 
sulphuric acid. There passes over into the 
receiver, first of all a liquor containing evi- 
dently acetic acid ; but towards the end of 
the distillation, there is condensed, in the 
vault of the retort, a white and foliated sub- 
limate, which is the pyrotartaric acid, per- 
fectly pure. 

It has a very sour taste, and reddens 
powerfully the tincture of turnsole. Heated 
in an open vessel, the acid rises in a white 
smoke, without leaving the charcoaly resi- 
duum which is left in a retort. It is very 
soluble in water, from which it is separated 
in crystals by spontaneous evaporation. The* 
bases combine with it, forming pyrotartrates, 
of which those of potash, soda, ammonia, 
baryta, strontia, and lime, are very soluble. 
That of potash is deliquescent, soluble in 
alcohol, capable of crystallizing in plates, like 
the acetate of potash. This pyrotartrate pre- 
cipitates both acetate of lead and nitrate of 
mercury, whilst the acid itself precipitates 
only the latter. Rose is the discoverer of 
this acid, which was formerly confounded 
with the acetic. 

ACID (RACENIC). An acid found 
associated with the tartaric in tartar, by M. 
Koestner. M. Gay Lussac observed that it 
took lime from the muriate of that base. It 
consists of 4 atoms of carbon, 5 of oxygen, 
and 2 of hydrogen. Its prime equivalent is 
8.307. It forms very remarkable salts ; that 
with potash and soda resembles Rochelle salt. 
M. Gay Lussac considers it to be isomor- 
phous with the tartaric acid. 

ACID (RHEUMIC). A supposed new 
acid extracted from the stems of rhubarb ; 
but it is merely the oxalic. 

ACID (ROSASIC). There is deposited 
from the urine of persons labouring under 
intermittent and nervous fevers, a sediment 
of a rose colour, occasionally in reddish crys- 
tals. This was first discovered to be a pecu- 
liar acid by M. Proust, and afterwards ex- 
amined by M. Vauquelin. This acid is solid, 



of a lively cinnabar hue, without smell, with 
a faint taste, bur reddening litmus very sen- 
sibly. On burning coal it is decomposed 
into a pungent vapour, which has not the 
odour of burning animal matter. It is very 
soluble in water, and it even softens in the 
air. It is soluble in alcohol. It forms solu- 
ble salts with potash, soda, ammonia, baryta, 
strontia, and lime. It gives a slight rose- 
coloured precipitate with acetate of lead. It 
also combines with lithic acid, forming so in- 
timate a union, that the lithic acid in preci- 
pitating from urine carries the other, though 
a deliquescent substance, down along with it. 
It is obtained pure by acting on the sedi- 
ment of urine with alcohol. See A cm (PuB- 
PIJRIC). 

ACID (SACLACTIC). See ACID (Mu- 
cic). 

ACID (SEBACIC). Subject to a con- 
siderable heat 7 or 8 pounds of hog's lard, in 
a stoneware retort capable of holding dou- 
ble the quantity, and connect its beak by an 
adopter with a cooled receiver. The conden- 
sible products are chiefly fat, altered by the 
fire, mixed with a little acetic and sebacic 
acids. Treat this product with boiling water 
several times, agitating the liquor, allowing 
it to cool, and decanting each time. Pour at 
last into the watery liquid, solution of acetate 
of lead in excess. A white flocculent preci- 
pitate of sebate of lead will instantly fall, 
which must be collected on a filter, washed 
and dried. Put the sebate of lead into a 
phial, and pour upon it its own weight of 
sulphuric acid, diluted with five or six times 
its weight of water. Expose this phial to a 
heat of about 212. The sulphuric acid 
combines with the oxide of lead, and sets the 
sebacic acid at liberty. Filter the whole 
while hot. As the liquid cools, the sebacic 
acid crystallizes, which must be washed, to 
free it completely from the adhering sulphu- 
ric acid. Let it be then dried at a gentle 
heat. 

The sebacic acid is inodorous ; its taste is 
slight, but it perceptibly reddens litmus pa- 
per ; its specific gravity is above that of water, 
and its crystals are small white needles of 
little coherence. Exposed to heat, it melts 
like fat, is decomposed, and partially evapo- 
rated. The air has no effect upon it. It is 
much more soluble in hot than in cold water ; 
hence boiling water saturated with it assumes 
a nearly solid consistence on cooling. Alco- 
hol dissolves it abundantly at the ordinary 
temperature. 

With the alkalis it forms soluble neutral 
salts ; but if we pour into their concencrated 
solutions, sulphuric, nitric, or muriatic acids, 
the sebacic is immediately deposited in large 
quantity. It affords precipitates with the 
acetates and nitrates of lead, mercury, and 
silver. 

Such is the account given by M. Thenard 



ACID 



94 



SUBERIC. 



of this acid, in the 3d volume of his Traite 
de Chimie, published in 1815. Berzelius, 
in 1816, published an elaborate dissertation 
to prove that M. Thenard's new sebacic acid 
was only the benzoic, contaminated by the 
fat, from which, however, it may be freed, 
and brought to the state of common benzoic 
acid. M. Thenard takes no notice of M. 
Berzelius whatever, but concludes his ac- 
count by stating, that it has been known only 
for twelve or thirteen years, and that it must 
not be confounded with the acid formerly 
called sebacic, which possesses a strong dis- 
gusting odour, and was merely acetic or mu- 
riatic acid ; or fat which had been changed, 
in some way or other, according to the pro- 
cess used in the preparation. 

ACID (SELENIC). There seems to 
be two acid compounds of selenium, a sele- 
nious and selenic acid ; the former is des- 
cribed under SELENIUM, the latter we shall 
describe here. This new compound was dis- 
covered by MM. Mitscherlich and Nitzsch. 
It contains half as much more oxygen as the 
old one discovered by M. Berzelius. 

Seleniate of lead is to be decomposed by 
sulphuretted hydrogen, and the selenic acid 
is disengaged. Its purity is ascertained by its 
entire volatility. If sulphuric acid be pre- 
sent, it may be detected by boiling a portion 
with muriatic acid, which produces selenious 
acid, and then testing by muriate of baryta ; 
a precipitate indicates sulphuric acid. 
From the decomposition of seleniate of pot- 
ash by muriate of baryta, it appeared that 
the seleniate was composed of 

Potash, 42.16 

Selenic acid, 57.84. 

100.00 

The composition of the acid was determined 
by boiling a certain weight of the seleniate 
of soda with muriatic acid in excess, and de- 
composing the selenious acid formed by sul- 
phite of soda ; 4.88 of the salt gave 2.02 of 
selenium, from which and the above result it 
would appear that the acid is formed of 
Selenium, 61.4 

Oxygen, 38.6 

100.0 

Selenic acid is a colourless liquid, which 
may be heated to 536 without sensible de- 
composition ; above that it changes, and at 
554 is rapidly resolved into oxygen and se- 
lenious acid. Heated to 329, its specific 
gravity is 2.524 ; at 512.6 it is 2.6. Sele- 
nic acid has a powerful attraction for water, 
and evolves much heat when mixed with it. 
When boiled with muriatic acid, it produces 
selenious acid and chlorine ; and the mixture, 
like aqua regia, will dissolve platina. Selenic 
acid dissolves zinc and iron, evolving hydro- 
gen ; it dissolves copper with disengagement 



of selenious acid, and of itself it dissolves 
gold, but not platina. 

Selenic acid is but little inferior, in affinity 
for bases, to sulphuric acid. Seleniate of 
baryta is not completely decomposed by sul- 
phuric acid. Its combinations being isomor- 
phous with those of sulphuric acid, and pos- 
sessing the same crystalline forms, and the 
same general chemical properties, exhibit but 
very slight differences from the sulphates. 

To prepare the seleniate of lead, the se- 
leniuret, freed from carbonates by muriatic 
acid, is to be fused with its weight of nitrate 
of soda in a red-hot crucible. Water then 
dissolves out seleniate, nitrate, and nitrite of 
soda. The solution quickly boiled, deposits 
anhydrous seleniate of soda. Or seleniate of 
soda may be fused with nitrate. The seleniate 
is decomposed by nitrate of lead ; whence re- 
sult insoluble seleniate of lead and nitrite of 
soda. See SELENIUM. 

ACID (SILICATED FLUORIC) 
See ACID (FLUORIC). 

ACID (SILVIC). A substance analo- 
gous to pinic acid, found in the resins of the 
pinus silvestris and fir tree. It is separated 
by acting on the resin several times with al- 
cohol, which takes up every thing but the 
silvic acid. The latter crystallizes almost en- 
tirely upon cooling, is colourless, and requires 
a higher temperature than 212 for its fu- 
sion. The crystals appear as quadrangular 
prisms. This acid dissolves in all propor- 
tions in volatile oils ; and the alcoholic solu- 
tion strongly reddens litmus. The silvate of 
copper is soluble in absolute alcohol, and 
may in that way be separated from the pinate 
of the same base. 

ACID (SOLANIC). Solania, which is 
principally contained in the berries of the 
common nightshade (solatium nigrum), is 
combined with a particular acid. This acid 
may be separated by means of ammonia, which 
precipitates the vegeto-alkali. It has a crys- 
talline form, is soluble in water, and produces 
crystallizable combinations with potash and 
soda ; the first in acicular crystals, the second 
in quadrilateral prisms, with a sweet taste. 

ACID (STEARIC). This acid is the 
saponified fat of mutton, beef, pork, &c. See 
FAT, and the details of its saponification. 

ACID (STIBIC). See ACID (ANTI- 

MONIC). 

ACID (STIBIOUS). See ACID (AN- 

TIMONIOUS). 

ACID (SUBERIC). M. Chevreul ob- 
tained the suberic acid by mere digestion of 
the nitric acid on grated cork, without distil- 
lation, and purified it by washing with cold 
water. 12 parts of cork may be made to 
yield 1 of acid. When pure, it is white and 
pulverulent, having a feeble taste, and little 
action on litmus. It is soluble in 80 parts 
of water at 55* F. and in 38 parts at 140. 



ACID 



SULPHOVINIC. 



It is much more soluble in alcohol, from 
which water throws down a portion of the 
suberic acid. It occasions a white precipitate 
when poured into acetate of lead, nitrates of 
lead, mercury and silver, muriate of tin, and 
protosulphateofiron. It affords no precipi- 
tate with solutions of copper or zinc. The 
suberates of potash; soda, and ammonia, are 
very soluble. The two latter may be readily 
crystallized. Those of baryta, lime, magne- 
sia, and alumina, are of sparing solubility. 

ACID(SUCCINIC). It has long been 
known that amber, when exposed to distilla- 
tion, affords a crystallized substance, which 
sublimes into the upper part of the vessel. 

M. Julin of Abo states, that by mixing with 
coarsely powdered amber 1-1 2th part of sul- 
phuric acid, diluted with an equal weight of 
water, the succinic acid will be produced in 
about twice the quantity got in the old way. 

Several processes have been proposed for 
purifying this acid : that of Richter appears 
to be the best. The acid being dissolved in 
hot water, and filtered, is to be saturated with 
potash or soda, and boiled with charcoal, 
which absorbs the oily matter. The solution 
being filtered, nitrate of lead is added ; whence 
results an insoluble succinate of lead, from 
which, by digestion in the equivalent quantity 
of sulphuric acid, pure succinic acid is sepa- 
rated. Nitrate or muriate of baryta will show 
whether any sulphuric acid remains mixed 
with the succinic solution ; and if so, it may 
be withdrawn by digesting the liquid with a 
little more succinate of lead. Pure succinic 
acid may be obtained by evaporation, in white 
transparent prismatic crystals. Their taste is 
somewhat sharp, and they redden powerfully 
tincture of turnsole. Heat melts and partially 
decomposes succinic acid. Air has no effect 
upon it. It is soluble in both water and 
alcohol, and much more so when they are 
heated. Its prime equivalent, by Berzelius, is 
6.26; and it is composed of 4.51 hydrogen, 
47.6 carbon, 47.888 oxygen, in 100, or 2 -f 
4 -f- 3 primes. 

With baryta and lime the succinic acid 
forms salt but little soluble ; and with mag- 
nesia it unites into a thick gummy substance. 
The succinates of potash and ammonia are 
crystallizahle and deliquescent ; that of soda 
does not attract moisture. The succinate of 
ammonia is useful in analysis to separate 
oxide of iron. 

ACID (SULPHOCYANIC.) See in 
the sequel of ACID (HYDROCYANIC). 

ACID (SULPHONAPHTHALIC). 
Mr Faraday communicated a paper, in 1826, 
to the Royal Society, to show that during the 
mutual action of sulphuric acid and naphtha- 
line, a compound of that acid with hydrocar- 
bon is formed, differing from all known sub- 
stances, and which, possessing acid properties, 
and combining with salifiable bases to pro- 



duce a peculiar class of salts, has been dis- 
tinguished as the sulphonaphthalic acid 

Let two parts of naphthaline and one part of 
concentrated sulphuric acid be introduced 
into a flask, raise the temperature till the 
naphthaline melts, and agitate. Combina- 
tion is effected, and, after cooling, two sub- 
stances are found, both in the solid state. 
The lighter is naphthaline, containing a little 
of the peculiar acid. The lower and heavier 
is also crystalline, but softer than the upper. 
It is red, of an acid bitter taste, absorbs 
moisture from the air, and consists principal- 
ly of the hydrated peculiar acid, containing 
some uncombined naphthaline. It is distin- 
guished as the impure solid acid. On rub- 
bing this with native carbonate of baryta in 
a mortar, a soluble barytic salt was obtained. 
To the solution of this salt, sulphuric acid 
was carefully added just in quantity sufficient 
to precipitate the baryta; and after filtration 
a pure aqueous solution of the new acid was 
obtained. This solution is bitter, acid, 
powerfully reddening vegetable blues, neu- 
tralizing bases, but not precipitating baryta 
or lead from their salts. When carefully 
evaporated in vacua, it affords a white, solid, 
crystalline acid, deliquescing in the air. It 
melts at 212 Fahr. and crystallizes on cool- 
ing. Its salts are soluble in water and al- 
cohol. That of baryta is composed of an 
atom of baryta, 2 of sulphuric acid, 20 of 
charcoal, and 8 of hydrogen. Its saturating 
power is equal to one-half that of its sul- 
phuric acid. 

ACID (SULPHOVINIC). The name 
given by Vogel to an acid, or class of acids, 
which may be obtained by digesting alcohol 
and sulphuric acid together with heat. Salts 
called sulphovinates were first noticed about 
the year 1800 by M. Dabit, and afterwards 
treated of by M. Vogel ; but their nature was 
never ascertained till Mr Hennel made his 
investigations lately on the subject. The 
sulphovinates are readily prepared by mixing 
equal weights of sulphuric acid and alcohol, 
allowing the mixture to remain for half an 
hour, then adding carbonate of lead equal in 
weight to that of sulphuric acid first used, 
and filtering ; little else than sulphovinic acid 
is left in solution. This combined with bases 
furnishes salts, which may be rendered pure 
by crystallization. Sulphovinic acid, accord- 
ing to Mr Hennel, consists of two atoms of 
sulphuric acid, four of hydrogen, and four of 
carbon ; and this compound acid combines 
with one atom of potash to form sulphovinate 
of potash. The vegetable part of the acid 
is therefore olefiant gas. Oil of wine and 
sulphovinic acid seern to be identical. Phil. 
Trans. 1826. Part 3. See OIL OF WINE. 

Messrs Dumas and Boullay state the com- 
position of sulphovinic acid, as analyzed in 
combination with baryta, to be 



ACID 



SULPHURIC. 




Sulphate of baryta, 
Sulphurous acid, 
Carbon, 
Hydrogen, 
Water, 



100.04 

The composition of the oily matter, brought 
to 100, would give 

Carbon, 88.37 
Hydrogen, 11.63 

100.00 

It is therefore oil of wine. This being ad- 
mitted, the sulphovinate of baryta is repre- 
sented by one atom of hyposulphate, two 
atoms of oil of wine, and five of water ; or 
Hyposulphate of baryta, 68.4 
Oil of wine, 12.25 

Water, 19.65 

100.30 

The authors then show that similar re- 
sults are obtained by analyzing the sulpho- 
vinates of copper and lead. 

ACID (SULPHURIC). Sulphuric acid 
was formerly obtained in this country by dis- 
tillation from sulphate of iron, as it still is in 
many parts abroad. The fluid that is thus 
obtained is the German sulphuric acid, of 
which Bernhardt got sixty-four pounds from 
six hundred weight of vitriol ; and on the 
other hand, when no water had been pre- 
viously poured into the receiver, fifty-two 
pounds only of a dry concrete acid. This 
acid was formerly called glacial oil of vitriol. 

It was shewn by Vogel, that when this 
fuming acid is put into a glass retort, and 
distilled by a moderate heat into a receiver 
cooled with ice, the fuming portion comes 
over first, and may be obtained in a solid state 
by stopping the distillation in time. This 
constitutes absolute sulphuric acid, or acid 
entirely void of water. It is in silky fila- 
ments, tough, difficult to cut, and somewhat 
like asbestos. Exposed to the air it fumes 
strongly, and gradually evaporates. It does 
not act on the skin so rapidly as concentrated 
oil of vitriol. Up to 66 it continues solid ; 
but at temperatures above this it becomes a 
colourless vapour, which whitens on contact 
with air. Dropped into water in small quan- 
tities, it excites a hissing noise, as if it were 
red-hot iron ; in larger quantities it produces 
a species of explosion. It is convertible into 
ordinary sulphuric acid, by the addition of 
water. It dissolves sulphur, and assumes a 
blue, green, or brown colour, according to 
the proportion of sulphur dissolved. The 
specific gravity of the black fuming sulphu- 
ric acid, prepared in large quantities from 
copperas at Nordhausen, is 1.896. 

The ordinary liquid acid of Nordhausen is 
brown, of variable density, and boils at 100 
or 120 F. One part of it evaporates in 



dense fumes, and the remainder is found to 
be common oil of vitriol. The above solid an- 
hydrous acid has a specific gravity of 1.97 at 
68 F. ; at 77 it remains fluid, and is less 
viscid than oil of vitriol. There is a little 
sulphurous acid present in that of Nordhau- 
sen, but it is accidental, and not essential to 
its constitution. The anhydrous acid makes 
a red solution of indigo. In the Journal of 
Science, xix. 62. I published the result of 
some experiments which I made to deter- 
mine the nature of the solid acid. The brown 
liquid acid has a specific gravity of 1.842. 
When distilled from a retort into a globe sur- 
rounded with ice, a white solid sublimate was 
received. When this sublimate was exposed 
to the air, it emitted copious fumes of sul- 
phuric (not sulphurous) acid. It burned 
holes in paper with the rapidity of a red-hot 
iron. By dropping a bit of it into a poised 
phial containing water, and stoppering in- 
stantly, to prevent the ejection of liquid by 
the explosive ebullition that ensues, I got a 
dilute acid containing a known portion of 
the solid acid, from the specific gravity of 
which, as well as its saturating power, I de- 
termined the constitution of the solid acid to 
be the anhydrous sulphuric ; or a compound 
of two by weight of sulphur, and three of 
oxygen. M. Gmelin states, in the Annales 
de Chimie et de Physique for June 1826, 
that on distilling sulphuric acid, if we change 
the receiver at the instant when it is filled with 
opaque vapours, and cover the new receiver 
with ice, we shall obtain anhydrous sulphu- 
ric acid, which is deposited in crystals on the 
inside of the vessel, and a less dense liquid 
acid, which remains in the retort. He sup- 
poses, that during the distillation the sulphu- 
ric acid is divided into two portions, one of 
which gives up its water to the other. 

The sulphuric acid made in Great Britain 
is produced by the combustion of sulphur in 
contact with a little nitre. 

The following ingenious theory of its for- 
mation was first given by MM. Clement and 
Desormes. The burning sulphur or sul- 
phurous acid, taking from the nitre a portion 
of its oxygen, forms sulphuric acid, which 
unites with the potash, and displaces a little 
nitrous and nitric acids in vapour. These 
vapours are decomposed by the sulphurous 
acid into nitrous gas, or deutoxide of azote. 
This gas, naturally little denser than air, and 
now expanded by the heat, suddenly rises to 
the roof of the chamber ; and might be ex- 
pected to escape at the aperture there, which 
manufacturers were always obliged to leave 
open, otherwise they found the acidification 
would not proceed : But the instant that ni- 
trous gas comes in contact with atmospherical 
oxygen, nitrous acid vapour is formed, which 
being a very heavy aeriform body, immedi- 
ately precipitates on the sulphurous flame, 
and converts it into sulphuric acid; while 



ACID 



SULPHURIC. 



itself, resuming the state of nitrous gas, re- 
ascends for a new charge of oxygen, again to 
redescend and transfer it to the flaming sul- 
phur. Thus we see, that a small volume of 
nitrous vapour, by its alternate metamor- 
phoses into the states of oxide and acid, and 
its consequent interchanges, may be capable 
of acidifying a great quantity of sulphur. 

This beautiful theory received a modifica- 
tion from Sir H. Davy. He found that ni- 
trous gas had no action on sulphurous gas, to 
convert it into sulphuric acid, unless water be 
present. With a small proportion of water, 
4> volumes of sulphurous acid gas, and 3 of 
nitrous gas are condensed into a crystalline 
solid, which is instantly decomposed by abun- 
dance of water : oil of vitriol is formed, and 
nitrous gas given off, which with contact of 
air becomes nitrous acid gas, as above de- 
scribed. The process continues, according to 
the same principle of combination and de- 
composition, till the water at the bottom of 
the chamber is become strongly acid. It is 
first concentrated in large leaden pans, and 
afterwards in glass retorts heated in a sand 
bath. Platinum alembics, placed within pots 
of cast-iron of a corresponding shape and 
capacity, have been lately substituted in many 
manufactories for glass, and have been found 
to save fuel, and quicken the process of con- 
centration. 

Dr Henry describes a peculiar substance, 
produced, during very cold weather, in the 
leaden pipe by which the foul air of a sul- 
phuric acid chamber was carried away. It 
was a solid resembling borax. It become soft 
and pasty in a warm room, and gradually a 
thick liquid of sp. gr. 1.831 floated over the 
solid part. The crystalline part Dr Henry 
considers as probably the same compound as 
MM. Clement and Desormes obtained by 
mingling sulphurous acid, nitrous gas, at- 
mospheric air, and aqueous vapour ; and he 
thinks its constitution is probably 

5 atoms sulphuric acid, - 25.00 
1 atom hyponitrous acid, - 4.75 
5 atoms water, 5.625 

35.375 

Ann. of Phil. xi. 368. 
The proper mode of burning the sulphur 
with the nitre, so as to produce the greatest 
quantity of oil of vitriol, is a problem, con- 
cerning which chemists hold a variety of opi- 
nions. M. Thenard describes the following 
as the best. Near one of the sides of the 
leaden chamber, and about a foot above its 
bottom, an iron plate, furnished with an up- 
right border, is placed horizontally over a 
furnace, whose chimney passes across, under 
the bottom of the chamber, without having 
any connexion with it. On this plate, which 
is enclosed in a little chamber, the mixture of 
sulphur and nitre is laid. The whole being 
shut up, and the bottom of the large cham- 



ber covered with water, a gentle fire is kindled 
in the furnace. The sulphur soon takes fire* 
and gives birth to the products described. 
When the combustion is finished, which is 
seen through a little pane adapted to the trap- 
door of the chamber, this is opened, the sul- 
phate of potash is withdrawn, and is replaced 
by a mixture of sulphur and nitre. The air 
in the great chamber is meanwhile renewed 
by opening its lateral door, and a valve in, 
its opposite side. Then, after closing these 
openings, the furnace is lighted anew. Suc- 
cessive mixtures are thus burned till the acid 
acquires a specific gravity of about 1.390, 
taking care never to put at once on the plate 
more sulphur than the air of the chamber can 
acidify. The acid is then withdrawn by stop- 
cocks, and concentrated. 

The ordinary form of a sulphuric acid lead 
chamber is the parallelepiped ; and its dimen- 
sions about seventy feet long, ten or twelve 
high, and sixteen wide. At the middle 
height of one end a small oven is built up, 
with a cast-iron sole, having a large lead 
pipe, ten or twelve inches diameter, proceed- 
ing from its arched top into the end of the 
lead chamber. On the sole the sulphur is 
burned, the combustion being aided, when 
necessary, by heat applied from a little fur- 
nace below it. Above the flaming sulphur 
a cast-iron basin is supported in an iron 
frame, into which the nitre, equal to one- 
tenth of the sulphur, is put, with a little sul- 
phuric acid. The combustion of the sulphur 
is regulated by a sliding door on the oven. 
In the roof of the remote end of the large 
chamber, a small orifice is left for the escape 
of the atmospherical azote, and other incon- 
densable gases. This apparatus is used for 
the continuous process. But there is an- 
other, or that of the intermitting combustion, 
which is worthy of notice. Large flat trays, 
containing the sulphur and nitre, are intro- 
duced into the interior of the chamber, or 
into the oven, and fire is applied to the ma- 
terials. When the sulphur is burned, and 
the chamber is replete with sulphurous and 
nitrous acids, the steam of water is -thrown 
in, in determinate quantity, by a small pipe 
at the side. This causes a tumultuous mo- 
tion among the gases and the atmospheric 
oxygen, which favours the mutual reaction. 
As the steam condenses, the sulphuric acid 
falls with it. After some time, the chamber 
is aired by opening valves of communication 
with the external atmosphere. The opera- 
tion is then commenced anew. 

Instead of using nitre, nitrous gas, disen- 
gaged from nitric acid by sugar or saw-dust, 
is introduced into the chamber containing the 
fumes of burning sulphur, whereby the che- 
mical reaction above described is produced ; 
and then steam is thrown in to complete the 
process, and condense the sulphuric acid. 
G 



ACID 



SULPHURIC. 



The bottom of the lead chamber should 
never be covered with pure water, but even 
in the first operation with a dilute acid, in- 
troduced on purpose. When nitrous acid 
comes into contact with water and an excess 
of atmospheric oxygen, it is converted into 
nitric acid and nitrous gas. This aeriform 
body gets more oxygen, and changes to nit- 
rous acid, and thereafter to nitric. Hence, 
a chamber with its bottom covered with water 
will, in some cases, fail in producing any 
sulphuric acid at all. Water, moderately 
charged with sulphuric and sulphurous acids, 
prevents the transition of the nitrous into 
nitric acid, and allows the process of acidifi- 
cation of the sulphur to go on freely. 

MM. Payen and Cartier disengage the 
nitrous gas in the midst of the burning sul- 
phur, from a mixture of nitric acid and starch 
contained in platinum basins. The main ob- 
jection to this process, is the difficulty of find- 
ing a market for the oxalic acid produced. 

Other chemists find, that it answers to in- 
troduce the vapour of nitric acid into the 
fumes of the burning sulphur, which con- 
verts it into nitrous acid ; but the simplest 
mode of effecting this object, is by the cast- 
iron basin placed over the burning sulphur, 
as already described. 

In burning the sulphur, care should be 
taken that it does not rise in flowers by mere 
sublimation ; to prevent which, the ingress 
of air should be proportional to the heat of 
the oven plate in the continuous process. 
The presence of sulphur in the acid would 
occasion great losses, were it not allowed to 
subside by repose ; for in the concentration 
of the sulphuric acid by heat, the sulphur 
would convert it into the sulphurous acid, 
which would be dissipated in the air. 

The following form of apparatus, as used 
by MM. Payen and Cartier, has been lately 
described in the Annales de V Industrie, t. i. 
It consists of a combustion oven, which com- 
municates with a first chamber; this sends 
forward its gases into a second, which leads 
to a third, and this to a fourth when neces- 
sary. But the fourth chamber does not im- 
mediately support the chimney, but commu- 
nicates with it by a long sloping canal. In 
the first chamber the acid is kept up at 
about 1.500; in the second at 1.370; and 
in the third at 1. 130. The floors of the se- 
veral chambers rise in succession, so that, by 
means of syphons, a portion of the acid may 
be drawn from the second to the first, and 
from the third to the second, in proportion 
as the acid is let off" out of the first for the 
purpose of concentration. Steam is also in- 
jected constantly into the terminal canal, and 
occasionally into each of the chambers, to fa- 
cilitate the condensation of acid. 

In comparing this and other forms of con- 
tinuous apparatus, with those where the com- 
bustion is made to intermit, it obviously pre- 



sents decided advantages. Each chamber is 
thus maintained at a temperature nearly uni- 
form, which saves the injuries often done to the 
plates of lead, by the too frequent and abrupt 
expansions and contractions in the intermit- 
ting plan. The nitre basins and trays are, 
for the same reason, not so rapidly wasted. 
The quantity of acid obtained is greater, by 
nearly a third, in a given time, with an equal 
capacity of chambers. The wages of labour 
is also less, as well as the fuel requisite for 
burning the sulphur. Indeed, the sulphur- 
pan or sole needs heating only at the com- 
mencement. The dose of nitre is reduced 
to 8 per cent. 

But nothing is easier than to combine the 
two systems, and to render these chambers 
intermittent, by gradually obstructing the in- 
gress of air into the combustion oven, then 
intercepting it altogether, and throwing in 
steam, condensing the acid vapours, and 
thereafter ventilating the air of the cham- 
bers. 

The following details are extracted from a 
paper on sulphuric acid, which I published in 
the 4th volume of the Journal of Science and 
the Arts. 

Commercial sulphuric acid often contains 
from one-half to three quarters of a part in 
the hundred, of solid saline matter foreign to 
its nature. These fractional parts consist of 
sulphate of potash and lead, in the propor- 
tion of four of the former to one of the lat- 
ter. The ordinary acid sold in the shops 
contains often three or four per cent of sa- 
line matter. Even more is occasionally in- 
troduced, by the employment of nitre, to re- 
move the brown colour given to the acid by 
carbonaceous matter. The amount of these 
adulterations, whether accidental or fraudu- 
lent, may be readily determined by evapo- 
rating in a small capsule of porcelain, or 
rather platinum, a definite weight of the acid. 
The platinum cup, placed on the red cinders 
of a common fire, will give an exact result 
in five minutes. If more than five grains of 
matter remain from five hundred of acid, we 
may pronounce it sophisticated. 

Distillation is the mode by which pure oil 
of vitriol is obtained. This process is des- 
cribed in chemical treatises as both difficult 
and hazardous ; but, since adopting the fol- 
lowing plan, I have found it perfectly safe 
and convenient. I take a plain glass retort, 
capable of holding from two to four quarts of 
water, and put into it about a pint measure 
of the sulphuric acid, (and a few fragments of 
glass), connecting the retort with a large glo- 
bular receiver, by means of a glass tube four 
feet long, and from one to two inches in dia- 
meter. The tube fits very loosely at both ends. 
The retort is placed over a charcoal fire, and 
the flame is made to play gently on its bot- 
tom. When the acid begins to boil smartly, 
sudden explosions of dense vapour rush forth 



ACID 



99 



SULPHURIC. 



from time to time, which would infallibly 
break small vessels. Here, however, these 
expansions are safely permitted, by the large 
capacity of the retort and receiver, as well as 
by the easy communication with the air at 
both ends of the adopter tube. Should the 
retort, indeed, be exposed to a great intensity 
of flame, the vapour will no doubt be gene- 
rated with incoercible rapidity, and break the 
apparatus. But this accident can proceed 
only from gross imprudence. It resembles, 
in suddenness, the explosion of gunpowder, 
and illustrates admirably Dr Black's obser- 
vation, that, but for the great latent heat of 
steam, a mass of water, powerfully heated, 
would explode on reaching the boiling tem- 
perature. I have ascertained, that the spe- 
cific caloric of the vapour of sulphuric acid 
is very small, and hence the danger to which 
rash operators may be exposed during its 
distillation. Hence, also, it is unnecessary 
to surround the receiver with cold water, as 
when alcohol and most other liquids are dis- 
tilled. Indeed the application of cold to the 
bottom of the receiver generally causes it, in 
the present operation, to crack. By the above 
method, I have made the concentrated oil of 
vitriol flow over in a continuous slender 
stream, without the globe becoming sensibly 
hot. 

I have frequently boiled the distilled acid 
till only one-half remained in the retort ; yet, 
at the temperature of 60 Fahrenheit, I have 
never found the specific gravity of acid so 
concentrated to exceed 1.8455. It is, I be- 
lieve, more exactly 1.8452. The number 
1.850, which it has been the fashion to assign 
for the density of pure oil of vitriol, is un- 
doubtedly very erroneous, and ought to be 
corrected. Genuine commercial acid should 
never surpass 1.8475: when it is denser, we 
may infer sophistication, or negligence, in 
the manufacture. 

The progressive increase of its density with 
saline contamination, will be shewn by the 
following experiments : To 4100 grains of 
genuine commercial acid (but concentrated 
to only 1.8350), 40 grains of dry sulphate of 
potash were added. When the solution was 
completed, the specific gravity at 60 had 
become 1.8417. We see that at these den- 
sities the addition of 0.01 of salt increases 
the specific gravity by about 0.0067. To 
the above 4140 grains other 80 grains of 
sulphate were added, and the specific gravity, 
after solution, was found to be 1.8526. We 
perceive that somewhat more salt is now re- 
quired to produce a proportional increase of 
density; 0.01 of the former changing the 
latter by only 0.0055. Five hundred grains 
of this acid being evaporated in a platinum 
capsule, left 16^ grains, whence the composi- 
tion wa 



Sulphate of potash, with a little sulphate of 

lead, - 3.30 

Water of dilution, - - 5.3 

Oil of vitriol of 1.8485, - 91.4 

100.0 

Thus, acid of 1.8526, which in commerce 
would have been accounted very strong, con- 
tained little more than 91 per cent of genu- 
ine acid. 

Into the last acid more sulphate of potash 
was introduced, and solution being favoured 
by digestion in a moderate heat, the specific 
gravity became, at 60, 1.9120. Of this 
compound, 300 grains, evaporated in the 
platinum capsule, left 41 grains of gently 
ignited saline matter. We have, therefore, 
nearly 14 per cent. On the specific gravity 
in this interval, an increase of 0.0054 was 
effected by 0.01 of sulphate. This liquid 
was composed of saline matter, - 14 
Water of dilution, - - 4.7 

Oil of vitriol of 1.8485, - 81.3 

100.0 

The general proportion between the density 
and impurity may be stated at 0.0055 of the 
former, to 0.01 of the latter. 

If from genuine oil of vitriol, containing ^ 
of a per cent of saline matter, a considerable 
quantity of acid be distilled off, what remains 
in the retort will be found very dense. At 
the specific gravity 1.865, such acid con- 
tains 3 of solid salt in the 100 parts. The 
rest is pure concentrated acid. From such 
heavy acid, at the end of a few days, some 
minute crystals will be deposited, after which 
its specific gravity becomes 1.860, and its 
transparency is perfect It contains about 
2,4- per cent of saline matter. Hence, if the 
chemist employ for his researches, an acid 
which, though originally pretty genuine, has 
been exposed to long ebullition, he will fall 
into great errors. From the last experiments 
it appears, that concentrated oil of vitriol can 
take up only a little saline matter in compa- 
rison with that which is somewhat dilute. 
It is also evident, that those who trust to 
specific gravity alone, for ascertaining the 
value of oil of vitriol, are liable to great im- 
positions. 

The saline impregnation exercises an im- 
portant influence on all the densities at sub- 
sequent degrees of dilution. Thus, the heavy 
impure concentrated acid, specific gravity 
1.8650, being added to water in the propor- 
tion of one part to ten by weight, gave, after 
twenty-four hours, a compound whose speci- 
fic gravity was 1.064. But the most concen- 
trated genuine acid, as well as distilled acid, 
by the same degree of dilution, namely 1 -\- 
10, acquires the specific gravity of only 
1.0602, while that of 1,852, containing, as 
stated above, 3^ per cent of sulphate of pot- 
ash combined with acid of 1.835, gives, on 



ACID 



100 



SULPHURIC. 



a similar dilution, 1.058. This difference, 
though very obvious to good instruments, is 
inappreciable by ordinary commercial appa- 
ratus. Hence this mode of ascertaining the 
value of an acid, recommended by Mr Dai- 
ton, is inadequate to detect a deterioration 
of even 8 or 9 per cent. Had a little more 
salt been present in the acid, the specific gra- 
vity of the dilute, in this case, would have 
equalled that of the genuine. On my aci- 
dimeter one per cent of deterioration could 
not fail to be detected, even by those igno- 
rant of science. 

The quantity of oxide, or rather sulphate 
of lead, which sulphuric acid can take up, is 
much more limited than is commonly ima- 
gined. To the concentrated oil of vitriol I 
added much carbonate of lead, and after di- 
gestion by a gentle heat, in a close vessel, for 
twenty-four hours, with occasional agitation, 
its specific gravity, when taken at 60, was 
scarcely greater than before the experiment. 
It contained about 0.005 of sulphate of lead. 

The quantity of water present in 100 parts 
of concentrated and pure oil of vitriol, seems 
to be pretty exactly 18.46. 

In the experiments executed to determine 
the relation between the density of diluted 
oil of vitriol and its acid strength, I 1 em- 
ployed a series of phials, numbered with a 
diamond. Into each phial, recently boiled 
acid, and pure water, were mixed in the suc- 
cessive proportions of 99 -|- 1, 98 -|- 2, 
97 _j_ 3, &c. through the whole range of di- 
gits down to 1 acid -f- 99 water. The phials 
were occasionally agitated during 24 hours, 
after which the specific gravity was taken. 
The acid was genuine and well concentrated. 
Its specific gravity was 1.8485. Some of 
the phials were kept with their acid contents 
for a week or two, but no further change in 
the density took place. The strongest pos- 
sible distilled acid was employed for a few 
points, and gave the same results as the 
other. 

Of the three well-known modes of ascer- 
taining the specific gravity of a liquid, name- 
ly, that by Fahrenheit's hydrometer; by 
weighing a vessel of known capacity filled 



with it; and by poising a glass ball, suspend- 
ed by a fine platina wire from the arm of a 
delicate balance I decidedly prefer the last. 
The corrosiveness, viscidity, and weight of 
oil of vitriol, render the first two methods 
ineligible ; whereas, by a ball floating in a 
liquid of which the specific gravity does not 
differ much from its own, the balance, little 
loaded, retains its whole sensibility, and will 
give the most accurate consistency of results. 

In taking the specific gravity of concen- 
trated or slightly diluted acid, the temperature 
must be minutely regulated, because, from 
the small specific heat of the acid, it is easily 
affected, and because it greatly influences the 
density. On removing the thermometer, it 
will speedily rise in the air to 75 or 80, 
though the temperature of the apartment be 
only 60. Afterwards it will slowly fall to 
perhaps 60 or 62. If this thermometer, 
having its bulb covered with a film of dilute 
acid (from absorption of atmospheric mois- 
ture), be plunged into a strong acid, it will 
instantly rise 10, or more, above the real 
temperature of the liquid. This source of 
embarrassment and x occasional error is obvi- 
ated by wiping the bulb after every immer- 
sion. An elevation of temperature, equal to 
10 Fahr. diminishes the density of oil of 
vitriol by 0.005; 1000 parts being heated 
from 60 to 212, become 1.043 in volume, 
as I ascertained by very careful experiments. 
The specific gravity, which was 1.848, be- 
comes only 1.772, being the number corres- 
ponding to a dilution of 1 4 per cent of water. 
The viscidity of oil of vitriol, which below 
50 is such as to render it difficult to deter- 
mine the specific gravity by a floating ball, 
diminishes very rapidly as the temperature 
rises, evincing that it is a modification of co- 
hesive attraction. 

The following Table of Densities, corres- 
ponding to degrees of dilution, was the re^ 
suit, in each point, of a particular experiment, 
and was moreover verified, in a number of 
its terms, by the further dilution of an acid 
previously combined with a known propor- 
tion of water. The balance was accurate 
and sensible. 



ACID 



101 



SULPHURIC. 



Table of the Quantity of Oil of Vitriol and Dry Sulphuric Acid in 100 
parts of Dilute, at different Densities, by DR URE. 



Liquid. 


Sp. Gr. 


Dry. 


Liquid 


Sp. Gr 


Dry. 


Liquid. 


Sp. Gr. 


Dry. 


100 


.8485 


81.54 


66 


1.5503 


53.82 


32 


1.2334 


26.09 


99 


.8475 


80.72 


65 


1.5390 


53.00 


31 


1.2260 


25.28 


98 


.8460 


79.90 


64 


1.5280 


52.18 


30 


1.2184 


24.46 


97 


.8439 


79.09 


63 


1.5170 


51.37 


29 


1.2108 


23.65 


96 


.8410 


78.28 


62 


1.5066 


50.55 


28 


.2032 


22.83 


95 


.8376 


77.46 


61 


1.4960 


49.74 


27 


.1956 


22.01 


94 


.8336 


76.65 


60 


1.4860 


48.92 


26 


.1876 


21.20 


93 


.8290 


75.83 


59 


1.4760 


48.11 


25 


.1792 


20.38 


92 


.8233 


75.02 


58 


1.4660 


47.29 


24 


.1706 


19.57 


91 


.8179 


74.20 


57 


1.4560 


46.48 


23 


.1626 


18.75 


90 


.8115 


73.39 


56 


1.4460 


45.66 


22 


.1549 


17.94 


89 


.8043 


72.57 


55 


1.4360 


44.85 


21 


.1480 


17.12 


88 


.7962 


71.75 


54 


1.4265 


44.03 


20 


.1410 


16.31 


87 


.7870 


70.94 


53 


1.4170 


43.22 


19 


1.1330 


15.49 


86 


.7774 


70.12 


52 


1.4073 


42.40 


18 


1.1246 


14.68 


85 


.7673 


69.31 


51 


.3977 


41.58 


17 


1.1165 


13.86 


84 


1.7570 


68.49 


50 


.3884 


40.77 


16 


1.1090 


13.05 


83 


1.7465 


67.68 


49 


.3788 


39.95 


15 


1.1019 


12.23 


82 


1.7360 


66.86 


48 


.3697 


39.14 


14 


1.0953 


10.41 


81 


1.7245 


66.05 


47 


.3612 


38.32 


13 


.0887 


11.60 


80 


1.7120 


65.23 


46 


.3530 


37.51 


12 


1.0809 


9.78 


79 


1.6993 


64.42 


45 


.3440 


36.69 


11 


1.0743 


8.97 


78 


1.6870 


63.60 


44 


.3345 


35.88 


10 


1.0682 


8.15 


77 


1.6750 


62.78 


43 


.3255 


35.06 


9 


.0614 


7.34 


76 


1.6630 


61.97 


42 


.3165 


34.25 


8 


1.0544 


6.52 


75 


1.6520 


61.15 


41 


.3080 


33.43 


7 


.0477 


5.71 


74 


.6415 


60.34 


40 


.2999 


32.61 


6 


.0405 


4.89 


73 


1.6321 


59.52 


39 


.2913 


31.80 


5 


1.0336 


4.08 


72 


.6204 


58.71 


38 


.2826 


30.98 


4 


1.0268 


3.26 


71 


.6090 


57.89 


37 


.2740 


30.17 


3 


1.0206 


2.446 


70 


1.5975 


57.08 


36 


.2654 


29.35 


2 


.0140 


1.63 


69 


1.5868 


56.26 


35 


.2572 


28.54 


1 


.0074 


0.8154 


68 


1.5760 


55.45 


34 


.2490 


27.72 








67 


1.5648 


54.63 


33 


.2409 


26.91 









In order to compare the densities of the 
preceding dilute acid, with those of distilled 
and again concentrated acid, I mixed one 
part of the latter with nine of pure water, 
and, after agitation, and a proper interval 
to ensure thorough combination, I found its 
specific gravity, as above, 1.0682: greater 
density indicates saline contamination. 

Dilute acid, having a specific gravity = 
1.6321, has suffered the greatest condensa- 
tion ; 100 parts in bulk have become 92. 14. 
If either more or less acid exist in the com- 
pound, the volume will be increased. What 
reason can be assigned for the maximum 
condensation occurring at this particular term 
of dilution ? The above dilute acid consists 
of 73 per cent of oil of vitriol, and 27 of 
water. But 73 of the former contains, by this 
table, 59.52 of dry acid, and 13.48 of water. 
Hence 100 of the dilute acid consist of 
59.52 of dry acid + 13.48 X 3= 40.44 of 
water = 99.96; or it is a compound of one 
atom of dry acid with three atoms of water. 



Dry sulphuric acid consists of three atoms 
of oxygen united to one of sulphur. Here 
each atom of oxygen is associated with one of 
water, forming a symmetrical arrangement. 
We may therefore infer, that the least devia- 
tion from the above definite proportions must 
impair the balance of the attractive forces, 
whence they will act less efficaciously, and 
therefore produce less condensation. 

The very minute and patient examination 
which I was induced to bestow on the table 
of specific gravities, disclosed to me the 
general law pervading the whole, and con- 
sequently the means of inferring at once the 
density from the degree of dilution, as also 
of solving the inverse proposition. 

If we take the specific gravity, correspond- 
ing to 10 per cent of oil of vitriol, or 1.0682 
as the root ; then the specific gravities, at the 
successive terms of 20, 30, 40, &c. will be 
the successive powers of that root. The terms 
of dilution are like logarithms, a series of 
numbers in arithmetical progression, corres- 



ACID 



102 



SULPHURIC. 



ponding to another series, namely, the spe- 
cific gravities in geometrical progression. 

The simplest logarithmic formula which I 
have been able to contrive is the following : 

Log. S= -, where S is the specific gra- 
vity, and a the per-centage of acid. 

And a = Log. S X 350. 

In common language the two rules may 
be stated thus : 

Problem 1st. To find the proportion of 
oil of vitriol in dilute acid of a given specific 
gravity. Multiply the logarithm of the spe- 
cific gravity by 350, the product is directly 
the per-centage of acid. 

If the dry acid be sought, we must multi- 
ply the logarithm of the specific gravity by 
285, and the product will be the answer. 

Problem 2d. To find the specific gravity 
corresponding to a given proportion of acid. 
Multiply the quantity of acid by 2, and 
divide by 700 ; the quotient is the logarithm 
of the specific gravity. 

TABLE of Distilled Sulphuric Acid for the 
higher points, below which it agrees with 
the former Table. 



Liquid Acid in 100. 

100 

95 

90 

85 
80 

75 



Sp. Gr. Dry Acid. 

1.84-6 81.63 

1.834 77.55 

1.807 73.47 

1.764 69.39 

1.708 65.30 



1.650 



61.22 



Sulphuric acid strongly attracts water, 
which it takes from the atmosphere very 
rapidly, and in larger quantities, if suffered 
to remain in an open vessel, imbibing one- 
third of its weight in twenty-four hours, and 
more than six times its weight in a twelve- 
month. If four parts by weight be mixed 
with one of water at 50, they produce an 
instantaneous heat of 300 F. ; and four 
parts raise one of ice to 212 : on the con- 
trary, four parts of ice, mixed with one of 
acid, sink the thermometer to 4 below 0. 
It requires a great degree of cold to freeze 
it ; and if diluted with half a part or more of 
water, unless the dilution be carried very far, 
it becomes more and more difficult to con- 
geal ; yet at the specific gravity of 1.78, or a 
few hundredths above or below this, it may 
be frozen by surrounding it with melting 
snow. Its congelation forms regular pris- 
matic crystals with six sides. Its boiling 
point, according to Bergman, is 540 ; ac- 
cording to Dalton, 590. 

Sulphuric acid consists of three prime 
equivalents of oxygen, one of sulphur, and 
one of water ; and by weight, therefore, of 
3.0 oxygen + 2.0 sulphur -f 1.125 water 
= 6. 125, which represents the prime equi- 
valent of the concentrated liquid acid ; while 
34-2=5, will be that of the dry acid. 



Pure sulphuric acid is without smell and 
colour, and of an oily consistence. Its ac- 
tion on litmus is so strong, that a single drop 
of acid will give to an immense quantity of 
water the power of reddening. It is a most 
violent caustic ; and has sometimes been ad- 
ministered with the most criminal purposes. 
The person who unfortunately swallows it, 
speedily dies in dreadful agonies and convul- 
sions. Chalk, or common carbonate of mag- 
nesia, is the best antidote for this, as well as 
for the strong nitric and muriatic acids. 

When transmitted through an ignited por- 
celain tube of one-fifth of an inch diameter, 
it is resolved into two parts of sulphurous 
acid gas, and one of oxygen gas, with water. 
Voltaic electricity causes an evolution of sul- 
phur at the negative pole ; whilst a sulphate 
of the metallic wire is formed at the positive. 
Sulphuric acid has no action on oxygen gas 
or air. It merely abstracts their aqueous 
vapour. 

If the oxygenized muriatic acid of M. 
Thenard be put in contact with the sulphate 
of ; silver, there is immediately formed in- 
soluble chloride of silver, and oxygenized 
sulphuric acid. To obtain sulphuric acid 
in the highest degree of oxygenation, it is 
merely necessary to pour baryta water into 
the above oxygenized acid, so as to precipi- 
tate only a part of it, leaving the rest in 
union with the whole of the oxygen. Oxy- 
genized sulphuric acid partially reduces the 
oxide of silver, occasioning a strong effer- 
vescence. See ACID. 

All the simple combustibles decompose 
sulphuric acid, with the assistance of heat. 
At about 400 Fahr. sulphur converts sul- 
phuric into sulphurous acid. Several metals 
at an elevated temperature decompose this 
acid, with evolution of sulphurous acid gas, 
oxidizement of the metal, and combination of 
the oxide with the undecomposed portion of 
the acid. 

Sulphuric acid is of very extensive use in 
the art of chemistry, as well as in metallurgy, 
bleaching, and some of the processes for dye- 
ing ; in medicine it is given as a tonic and 
stimulant, and is sometimes used externally 
as a caustic. 

The combinations of this acid with the 
various bases are called sulphates, and most 
of them have long been known by various 
names. With baryta it is found native and 
nearly pure, in various forms. (See HEAVY 
SPAR. ) It may be artificially formed by drop- 
ping a. solution of an alkaline sulphate into 
the solution of muriate or nitrate of baryta. 
It forms a white powder which suffers no 
change by the action of the air, and is there- 
fore sometimes used in water-colour painting. 

It consists, according to Dr Wollaston, of 
5 parts of dry acid, and 9.75 of baryta. It 
requires 43.000 parts of water to dissolve it 
at 60. 



ACID 



103 



SULPHURIC. 



Sulphate of strontia has a considerable re- 
semblance to that of baryta in its properties. 
It is found native in considerable quantities 
at Aust Passage and other places in the 
neighbourhood of Bristol. It requires 3840 
parts of boiling water to dissolve it. 

Its composition is 5 acid -J- 6.5 base. 

Sulphate of potash, formerly vitriolated 
tartar, crystallizes in hexaedral prisms, ter- 
minated by hexagonal pyramids, but suscep- 
tible of variations. Its crystallization by quick 
cooling is confused. Its taste is bitter, acrid, 
and a little saline. It is soluble in five parts 
of boiling water, and sixteen parts at 60. 
In the tire it decrepitates, and is fusible by a 
strong heat. It is decomposable by charcoal 
at a high temperature. It may be prepared 
by direct mixture of its component parts ; 
but the usual and cheapest mode is to ignite 
the acidulous sulphate left after distilling ni- 
tric acid. The sal poly chrest of old dispen- 
satories, made by deflagrating sulphur and 
nitre in a crucible, was a compound of the 
sulphate and sulphite of potash. The aci- 
dulous sulphate is sometimes employed as a 
flux, and likewise in the manufacture of alum. 
In medicine the neutral salt is sometimes used 
as a mild cathartic. 

It consists of 5 acid -f- 6 base ; but there 
is a compound of the same constituents, in 
the proportion of 10 acid -}- 6 potash, called 
the bi-sulphate. 

Sulphate of soda is the well known Glau- 
ber's salt. It is commonly prepared from the 
residuum left after distilling muriatic acid, 
the superfluous acid of which may be expell- 
ed by ignition ; and is likewise obtained in 
the manufacture of the muriate of ammonia. 
(See AMMONIA.) It exists in large quanti- 
ties under the surface of the earth in some 
countries, as Persia, Bohemia, and Switzer- 
land ; is found mixed with other substances 
in mineral springs and sea water ; and some- 
times effloresces on walls. Sulphate of soda 
is bitter and saline to the taste. It is soluble 
in 2.85 parts of cold water, and 0.8 at a 
boiling heat. It crystallizes in hexagonal 
prisms bevelled at the extremities, sometimes 
grooved longitudinally, and of very large size, 
when the quantity is great : these effloresce 
completely into a white powder if exposed to 
a dry air, or even if kept wrapped up in pa- 
per in a dry place ; yet they retain sufficient 
water of crystallization to undergo the aque- 
ous fusion on exposure to heat, but by urg- 
ing the fire, melt. Baryta and strontia take 
its acid from it entirely, and potash partially : 
the nitric and muriatic acids, though they 
have a weaker affinity for its base, combine 
with a part of it when digested on it. Heat- 
ed with charcoal its acid is decomposed. As 
a purgative its use is very general ; and it 
has been employed to furnish soda. Pajot 
des Charmes has made some experiments on 
it in fabricating glass: with sand alone it 



would not succeed, but equal parts of car- 
bonate of lime, sand, and dried sulphate of 
soda, produced a clear, solid, pale yellow 
glass. 

It is composed of 5 acid -\- 4> base -f- 
1 1.25 water in crystals ; when dry, the former 
two primes are its constituents. 

A difference in the temperature at which 
a solution of sulphate of soda is evaporated, 
will cause the formation of the ordinary hy- 
drated crystals or anhydrous crystals, at plea- 
sure. When hydrated crystals of soda are 
carefully melted, a portion dissolves and a 
portion separates ; the latter in an anhydrous 
state. 

Sulphate of soda and sulphate of ammonia 
form together a triple salt. 

Sulphate of lime, selenite, gypsum, plaster 
of Paris, or sometimes alabaster, forms ex- 
tensive strata in various mountains. See 
GYPSUM. 

It requires 500 parts of cold water, and 
450 of hot, to dissolve it. When calcined, it 
decrepitates, becomes very friable and white, 
and heats a little with water, with which it 
forms a solid mass. In this process it loses 
its water of crystallization. The calcined sul- 
phate is much employed for making casts of 
anatomical and ornamental figures ; as one 
of the bases of stucco ; as a fine cement for 
making close and strong joints between stone, 
and joining rims or tops of metal to glass ; 
for making moulds for the Staffordshire pot- 
teries; for cornices, mouldings, and other 
ornaments in building. For these purposes, 
and for being wrought into columns, chim- 
ney-pieces, and various ornaments, about eight 
hundred tons are raised annually in Derby- 
shire, where it is called alabaster. In Ame- 
rica it is laid on grass land as a manure. 

Ordinary crystallized gypsum consists of 
5 sulphuric acid -j- 3.5 lime -f- 2.25 water; 
the anhydrous variety wants of course the last 
ingredient. 

Sulphate of magnesia is commonly known 
by the name of Epsom salt, as it was fur- 
nished in considerable quantity by the mine- 
ral water at that place, mixed, however, with 
a considerable portion of sulphate of soda. 
It is afforded, however, in greater abundance, 
and more pure, from the bittern left after the 
extraction of salt from sea water. It has like- 
wise been found efflorescing on brick walls, 
both old and recently erected, and in small 
quantity in the ashes of coals. The capil- 
lary salt of Idria, found in silvery crystals 
mixed with the aluminous schist in the mines 
of that place, and hitherto considered as a 
feathery alum, has been ascertained by Klap- 
roth to consist of sulphate of magnesia, mix- 
ed with a small portion of sulphate of iron. 
When pure it crystallizes in small quadran- 
gular prisms, terminated by quadrangular 
pyramids or diedral summits. Its taste is 
cool and bitter. It is very soluble, requiring 



ACID 



104 



SULPHUROUS. 



only an equal weight of cold water, and three- 
fourths its weight of hot. It effloresces in 
the air, though but slowly. If it attract mois- 
ture, it contains muriate of magnesia or of 
lime. Exposed to heat, it dissolves in its 
own water of crystallization, and dries, but is 
not decomposed, nor fused, but with extreme 
difficulty. It consists, according to Berg- 
man, of 33 acid, 1 9 magnesia, 48 water. A 
very pure sulphate is said to be prepared in 
the neighbourhood of Genoa, by roasting a 
pyrites found there, exposing it to the air in 
a covered place for six months, watering it 
occasionally, and then lixiviating. 

Sulphate of magnesia is one of our most 
valuable purgatives ; for which purpose only 
it is used, and for furnishing the carbonate of 
magnesia. 

It is composed of 5 acid + 2.5 magnesia 
-f- 7.875 water, in the state of crystals. 

Sulphate of ammonia crystallizes in slen- 
der, flattened, hexaedral prisms, terminated 
by hexagonal pyramids; it attracts a little 
moisture from very damp air, particularly if 
the acid be in excess ; it dissolves in two parts 
of cold and one of boiling water. It is not 
used, though Glauber, who called it his secret 
ammoniacal salt, vaunted its excellence in 
assaying. 

It consists of 5 acid -}- 2. 125 ammonia -f- 
1.125 water in its most desiccated state ; and 
in its crystalline state of 5 acid -\- 2. 125 am- 
monia -f- 3.375 water. 

If sulphate of ammonia and sulphate of 
magnesia be added together in solution, they 
combine into a triple salt of an octaedral 
figure, but varying much ; less soluble than 
either of its component parts ; unalterable in 
the air ; undergoing on the fire the watery 
fusion ; after which it is decomposed, part of 
the ammonia flying off, and the remainder 
subliming with an excess of acid. It con- 
tains, according to Fourcroy, 68 sulphate of 
magnesia and 32 sulphate of ammonia. 

Sulphate of glucina crystallizes with diffi- 
culty, its solution readily acquiring and re- 
taining a syrupy consistence ; its taste is sweet, 
and slightly astringent ; it is not alterable in 
the air; a strong heat expels its acid, and 
leaves the earth pure; heated with charcoal 
it forms a sulphuret ; infusion of galls forms 
a yellowish-white precipitate with its solu- 
tion. 

Yttria is readily dissolved by sulphuric 
acid ; and as the solution goes on, the sul- 
phate crystallizes in small brilliant grains, 
which have a sweetish taste, but less so than 
sulphate of glucina, and are of a light ame- 
thyst-red colour. They require 30 parts of 
cold water to dissolve them, and give up their 
acid when exposed to a high temperature. 
They are decomposed by oxalic acid, prus- 
siate of potash, infusion of galls, and phos- 
phate of soda. 

Sulphate of alumina in its pure state is but 



recently known, and it was first attentively 
examined by Vauquelin. It may be made 
by dissolving pure alumina in pure sulphuric 
acid, heating them for some time, evaporat- 
ing the solution to dryness, drying the resi- 
duum with a pretty strong heat, redissolving 
it, and crystallizing. Its crystals are soft, 
foliaceous, shining, and pearly ; but these are 
not easily obtained without cautious evapora- 
tion and refrigeration. They have an astrin- 
gent taste ; are little alterable in the air ; are 
pretty soluble, particularly in hot water; give 
out their acid on exposure to a high tempe- 
rature ; are decomposable by combustible sub- 
stances, though not readily ; and do not form 
a pyrophorus like alum. 

If the evaporation and desiccation directed 
above be omitted, the alumina will remain 
supersaturated with acid, as may be known 
by its taste, and by its reddening vegetable 
blue. This is still more difficult to crystal- 
lize than the neutral salt, and frequently 
thickens into a gelatinous mass. 

A compound of acidulous sulphate of alu- 
mina with potash or ammonia has long been 
known by the name of ALUM. See ALU- 
MINA. 

If this acidulous sulphate or alum be dis- 
solved in water, and boiled with pure alu- 
mina, the alumina will become saturated with 
its base, and fall down an insipid white pow- 
der. This salt is completely insoluble, and 
is not deprived of its acid by heat but at a 
very high temperature. It may be decom- 
posed by long boiling with the alkaline or 
earth bases ; and several acids convert it into 
common alum, but slowly. 

Sulphate of zirconia may be prepared by 
adding sulphuric acid to the earth recently 
precipitated, and not yet dry. It is sometimes 
in small needles, but commonly pulverulent ; 
very friable ; insipid ; insoluble in water, un- 
less it contain some acid; and easily decom- 
posed by heat. 

ACID (SULPHUROUS). This acid is 
formed by the ordinary combustion of sul- 
phur in the open air ; but it can be obtained 
most purely and conveniently by digesting 
mercury in sulphuric acid, with heat, in a re- 
tort. The metal becomes oxidized, and sul- 
phurous acid gas is disengaged with effer- 
vescence. M. Berthier has recently shewn 
that sulphurous acid gas may be obtained 
very pure, and abundantly, by heating a mix- 
ture of twelve or fourteen parts of sublimed 
sulphur, and a hundred parts of peroxide of 
manganese, in a glass retort. The residue in 
the retort is not a sulphuret of manganese, 
but a protoxide of that metal, mixed with a 
little sulphate, and sometimes a little sulphur. 
Ann. de Chim. et de Phys. xxiv. 275. 

The gas may be collected over quicksilver, 
or received into water, which, at the tempe- 
rature of 61, will absorb 33 times its bulk, 
or nearly an eleventh of its weight. 



ACID 



105 



HYPOSULPHUROUS. 



Water thus saturated is intensely acid to 
the taste, and has the smell of sulphur burn- 
ing slowly. It destroys most vegetable co- 
lours ; but the blues are reddened by it pre- 
vious to their being discharged. A pleasing 
instance of its effect on colours may be ex- 
hibited by holding a red rose over the blue 
flame of a common match, by which the co- 
lour will be discharged wherever the sulphur- 
ous acid comes into contact with it, so as to 
render it beautifully variegated, or entirely 
white. If it be then dipped into water, the 
redness after a time will be restored. 

The specific gravity of sulphurous acid 
gas, as given by MM. Thenard and Gay 
Lussac, is 2. 2558, but by Sir H. Davy is 
2.2295, and hence 100 cubic inches weigh 
68 grains; but its spec. gr. most probably 
should be estimated at 2.222, and the weight 
of 100 cubic inches will become 67.777. Its 
constituents by volume are, one of oxygen, 
and one of vapour of sulphur; each having 
a spec. gr. of 1.111, condensed so that both 
volumes occupy only one. Or, in popular 
language, sulphurous acid may be said to 
be a solution of sulphur in oxygen, which 
doubles the weight of this gas without aug- 
menting its bulk. It obviously, therefore, 
consists by weight of equal quantities of the 
two constituents. Its equivalent will either 
be 2 oxygen -J- 2 sulphur = 4.0 ; or 1 oxy- 
gen -f- 1 sulphur = 2. Now the analysis of 
sulphite of baryta by Ber/elius gives 209. 22 
base to 86.53 acid; which being reduced, 
presents for the prime equivalent of sulphur- 
ous acid the number 4. Hydrogen and car- 
bon readily decompose sulphurous acid at a 
red heat, and even under it. Mr Higgins 
discovered, that liquid sulphurous acid dis- 
solves iron, without the evolution of any gas. 
The peroxides of lead and manganese furnish 
oxygen to convert it into sulphuric acid, which 
forms a sulphate with the resulting metallic 
protoxide. 

Sulphurous acid is used in bleaching, par- 
ticularly for silks. It likewise discharges ve- 
getable stains and iron-moulds from linen. 

In combination with the salifiable bases, it 
forms sulphites, which differ from the sul- 
phates in their properties. The alkaline sul- 
phites are more soluble than the sulphates, 
the earthy less. They are converted into sul- 
phates by an addition of oxygen, which they 
acquire even by exposure to the air. The 
sulphite of lime is the slowest to undergo 
this change. A strong heat either expels their 
acid entirely, or converts them into sulphates. 
They have all a sharp, disagreeable, sulphur- 
ous taste. The best mode of obtaining them 
is by receiving the sulphurous acid gas into 
water holding the base, or its carbonate, 
in solution, or diffused in it in fine powder. 
None of them has yet been applied to any 
use in the arts. 

By putting sulphuric acid and mercury 



into the sealed end of a glass tube recurved, 
then sealing the other end, and applying heat 
to the former, Mr Faraday obtained a liquid 
sulphurous acid. (PA. Tr. 1823.) M. Bus- 
sy {Ann. de Chim. for May 1824) says, that 
he liquefied the same gas, by transmitting it 
through fused chloride of calcium into a flask 
surrounded with a mixture of ice and salt. 
It remains in a liquid state in the air at the 
temperature of F. It is a colourless, trans- 
parent, and very volatile liquid, of a specific 
gravity = 1.45. It boils at 14 F. ; but in 
consequence of the cold produced by the eva- 
poration of the portion that flies off, the re- 
sidue remains liquid. It causes a feeling of 
intense cold when dropped on the hand. By 
evaporation of the acid in vacua, M. Bussy 
froze alcohol, sp. gr. 0.850. 

M. A. de la Hive, while experimenting 
upon the liquefaction of sulphurous acid by 
cold, remarked the formation of crystals in 
several cases, which he afterwards found to 
be hydrated sulphurous acid, analogous to 
those of hydrate of chlorine. 

ACID (HYPOSULPHUROUS). In 
the 85th volume of the Annales de Chimie, 
M. Gay Lussac describes permanent crystal- 
lizabfl|fc salts having lime and strontia for 
their base, combined with an acid of sulphur, 
in which the proportion of oxygen is less than 
in sulphurous acid ; but this acid he does not 
seem to have examined in a separate state. 
Those salts were procured by exposing solu- 
tions of the sulphurets of the earths to the 
air, when sulphur and carbonate of lime pre- 
cipitated. When the filtered liquid is then 
evaporated, and cooled, colourless crystals 
form. The calcareous are prismatic needles, 
and those with strontia are rhomboidal. He 
called these new compounds sulphuretted sul- 

phites. Those of potash and soda he also 
formed by heating their sulphites with sul- 
phur; when a quantity of sulphurous acid 
was disengaged, and neutral salts were form- 
ed. M. Gay Lussac farther informs us, that 
boiling a solution of a sulphite with sulphur, 
determines the formation of the sulphuretted 
sulphite, or hyposulphite ; and that iron, zinc, 
and manganese, treated with liquid sulphur- 
ous acid, yield sulphuretted sulphites : from 
which it follows, that a portion of the sul- 
phurous acid is decomposed by the metal, 
and that the resulting oxide combines with 
the other portion of the sulphurous acid and 
the liberated sulphur. The hyposulphites are 
more permanent than the sulphites ; they do 
not readily pass by the action of the air into 
the state of sulphate ; and though decompos- 
able at a high heat, they resist the action of 
fire longer than the sulphites. They are de- 
composed in solution by the sulphuric, mu- 
riatic, fluoric, phosphoric, and arsenic acids ; 
sulphurous acid is evolved, sulphur is preci- 
pitated, and a new salt is formed. Such is 
the account given of these by M. Gay Lussac, 



ACID 



106 



HYPOSULPHUROUS. 



and copied into the second volume of the 
Traite de Chimie of M. Thenard, published 
in 1814.. 

No additional information was communi- 
cated to the world on this subject till January 
1819, when an ingenious paper on the hypo- 
sulphites appeared in the Edinburgh Philo- 
sophical Journal, followed soon by two others 
in the same periodical work, by Mr Hers- 
chel. 

In order to obtain hyposulphurous acid, 
Mr Herschel mixed a dilute solution of hy- 
posulphite of strontia with a slight excess 
of dilute sulphuric acid, and after agitation 
poured the mixture on three filters. The 
tirst was received into a solution of carbonate 
of potash, from which it expelled carbonic 
acid gas. The second portion being received 
successively into nitrates of silver and mer- 
cury, precipitated the metals copiously in the 
state of sulphurets, but produced no effect on 
solutions of copper, iron, or zinc. The third, 
being tasted, was acid, astringent, and bitter. 
When fresh filtered, it was clear ; but it be- 
came milky on standing, depositing sulphur, 
and exhaling sulphurous acid. A moderate 
exposure to air, or a gentle heat, caused its 
entire decomposition. 

The habitudes of oxide of silver in union 
with this acid, are very peculiar. Hyposul- 
phite of soda being poured on newly precipi- 
tated oxide of silver, hyposulphite of silver 
was formed, and caustic soda eliminated ; 
the only instance, says Mr Herschel, yet 
known, of the direct displacement of a fixed 
alkali by a metallic oxide, via humida. On 
the other hand, hyposulphurous acid, newly 
disengaged from the hyposulphite of baryta 
by dilute sulphuric acid, readily dissolved, and 
decomposed muriate of silver, forming a sweet 
solution, from which alcohol separated the 
metal in the state of hyposulphite. " Thus 
the affinity between this acid and base, 
unassisted by any double decomposition, is 
such as to form an exception to all the ordi- 
nary rules of chemical union." This acid 
has a remarkable tendency to form double 
salts with the oxides of silver and alkaline 
bases. The hyposulphite of silver and soda 
has an intensely sweet taste. When hyposul- 
phite of ammonia is poured on muriate of 
silver, it dissolves it; and if into the saturated 
solution alcohol be poured, a white salt is 
precipitated, which must be forcibly squeezed 
between blotting paper, and dried in vacuo. 
It is very soluble in water. Its sweetness is 
unmixed with any other flavour, and so in- 
tense as to cause pain in the throat. One 
grain of the salt communicates a perceptible 
sweetness to 32,000 grains of water. If the 
alcoholic liquid be evaporated, thin lengthen- 
ed hexangular plates are sometimes formed, 
which are not altered by keeping, and consist 
of the same principles. 

The best way of obtaining the alkaline 



hyposulphites, is to pass a current of sulphu- 
rous acid gas through a lixivium formed by 
boiling a watery solution of alkali, or alkaline 
earth, along with sulphur. The whole of the 
sulphurous acid is converted into the hypo- 
sulphite, and pure sulphur, unmixed with any 
sulphite, is precipitated, while the hyposul- 
phite remains in solution. 

Mr Herschel, from his experiments on the 
hyposulphite of lime, has deduced the prime 
equivalent of hyposulphurous acid to be 
59.25. He found that 100 parts of crystal- 
lized hyposulphite of lime were equivalent to 
121.77 hyposulphite of lead, and yielded of 
carbonate of lime, by carbonate of ammonia, 
a quantity equivalent to 21.75 gr. of lime. 
Therefore the theory of equivalent ratios 
gives us this rule : . 

As 21.75 gr. lime are to its prime equiva- 
lent 3. 5, so are 12l.77gr. of hyposulphite of 
lead to its prime equivalent. In numbers 
21.75 : 3.5 :: 121.77 : 19.6. From this 
number, if we deduct the prime of the oxide 
of lead = 14, the remainder 5.6 will be the 
double prime of hyposulphurous acid. Now 
this number does not differ very far from 6. 
Hence we see that the hyposulphites, for 
their neutral condition, require of this feeble 
acid 2 prime proportions. One prime pro- 
portion of it is obviously made up of one 
prime of sulphur = 2, -j- 1 oxygen = 1 ; 
and the acid equivalent is = 3. The crys- 
tallized hyposulphite of lime is composed of 
6 acid -J- 3.5 lime -{- 6.75 water, being six 
primes of the last constituent. 

It ought to be stated, that when a solution 
of a hyposulphite is boiled down to a certain 
degree of concentration, it begins to be rapidly 
decomposed, with the deposition of sulphur 
and sulphite of lime. To obtain the salt in 
crystals, the solution must be evaporated at a 
temperature not exceeding 140 Fahr. If it 
be then filtered while hot, it will yield, on 
cooling, large and exceedingly beautiful crys- 
tals, which assume a great variety of compli- 
cated forms. They are soluble in nearly 
their own weight of water at 37 Fahr. and 
the temperature of the solution falls to 31. 
The specific gravity of their saturated solution 
at 60 is 1.300; and when it is 1.1 14, the 
liquid contains one-fifth of its weight. The 
crystals are permanent in the air. 

Hyposulphites of potash and soda yield de- 
liquescent crystals of a bitter taste, and both 
of them dissolve muriate of silver. The am- 
moniacal salt is not easily procured in regu- 
lar crystals. Its taste is pungent and disa- 
greeable. The barytic hyposulphite is inso- 
luble; the strontitic is soluble and crystal- 
lizable. Like the other hyposulphites, it 
dissolves silver; and while its own taste is 
purely bitter, it produces a sweet compound 
with muriate of silver, which alcohol throws 
down in a syrupy form. Hyposulphite of 
magnesia is a bitter tasted, soluble, crystal- 



ACID 



107 



HYPOSULPHURIC. 



lizable, and nondeliquescent salt. All the 
hyposulphites burn with a sulphurous flame. 
The sweetness of liquid hyposulphite of 
soda, combined with muriate of silver, sur- 
passes honey in intensity, diffusing itself 
over the whole mouth and fauces without 
any disagreeable or metallic flavour. A coil 
of zinc wire speedily separates the silver in a 
metallic state, thus affording a ready analysis 
of muriate of silver. Muriate of lead is 
also soluble in the hyposulphites, but less 
readily. 

ACID (HYPOSULPHURIC). MM. 
Gay Lussac and Welther have recently an- 
nounced the discovery of a new acid combi- 
nation of sulphur and oxygen, intermediate 
between sulphurous and sulphuric acids, to 
which they have given the name of hyposul- 
phuric acid. It is obtained by passing a 
current of sulphurous acid gas orer the black 
oxide of manganese. A combination takes 
place ; the excess of the oxide of manganese 
is separated by dissolving the hyposulphate of 
manganese in water. Caustic baryta preci- 
pitates the manganese, and forms with the 
new acid a very soluble salt, which, freed 
from excess of baryta by a current of car- 
bonic acid, crystallizes regularly, like the 
nitrate or muriate of baryta. Hyposulphate 
of baryta being thus obtained, sulphuric acid 
is cautiously added to the solution, which 
throws down the baryta, and leaves the hypo- 
sulphuric acid in the water. This acid 
bears considerable concentration under the 
receiver of the air-pump. It consists of five 
parts of oxygen to four of sulphur. The 
greater number of the hyposulphates, both 
earthy and metallic, are soluble, and crystal- 
lize ; those of baryta and lime are unalterable 
in the air. Suberic acid and chlorine do not 
decompose the barytic salt. The barytic salt 
in crystals consists of baryta 9.75 -j- hyposul- 
phuric acid 9.00 + water 2.25= 20^95. 

Dr Heeren prepares hyposulphuric acid 
nearly as above described ; but he separates 
the sulphuric acid and oxide of manganese 
in solution by sulphuret of barium instead of 
baryta water; because the latter does not 
completely remove the oxide of manganese. 
To take away the excess of sulphuret of 
barium, he passes carbonic acid through the 
mixture, applies heat, and filters ; and the 
fluid, by due concentration, yields pure crys- 
tals of hyposulphate of baryta. Being de- 
composed by sulphuric acid, the hyposul- 
phuric acid is obtained pure. To obtain the 
largest quantity of this product, the peroxide 
of manganese should contain no deutoxide, 
should be in exceedingly fine powder, and 
the whole kept at as low a temperature as 
possible. Anhydrous liquid sulphurous acid 
has no action on the peroxide of manganese. 
The following are the characters of some 
hyposulphates : 

Potash; fine crystals; anhydrous; bkter; 



unchanged in air ; insoluble in alcohol ; 
soluble in 1.58 of boiling water, and in 26.5 
of water at 60. 

Soda ; large quadrangular prisms ; bitter ; 
unchanged in air ; contain 15.54 per cent of 
water; soluble in 1.1 water at 212 Fahr. 
and in 2. 1 water at 60. 

Ammonia; difficultly crystallizable ; cool 
taste ; unchanged in air ; dissolves in less 
than one of water ; by heat loses water, and 
is then decomposed; contains 18.44 per cent 
of water. 

Baryta ; two kinds of crystals ; 10.78 per 
cent water ; bitter and astringent ; unchanged 
in air ; decrepitates by heat ; soluble in 
1.1 boiling water, and in 4.04 of water at 
64. 

Strontia ; large hexagonal tables; 22.1 
per cent of water ; bitter; unchanged in air ; 
not so soluble as the last salt. 

Lime ; in appearance resembles the last ; 
bitter ; 26.24 per cent of water ; dissolves in 
0.8 boiling water; and in 2.46 of water at 
56 F. 

Magnesia ; hexagonal prisms ; unchange- 
able in air; ver/ bitter ; fusible; 37.69 per 
cent of water ; very soluble. 

The metallic oxides all form salts with this 
acid ; and all the salts, as Gay Lussac has 
shewn, are soluble in water, and insoluble in 
alcohol. 

The following table exhibits the composi- 
tion of the different acid compounds of sul- 
phur and oxygen : 

Hyposulphurous acid, 20 sul. -f- 10 oxygen 
Sulphurous acid, 10 -f- 10 

Hyposulphuric acid, 8 4-10 
Sulphuric acid, 6| -f- 10 

Or, if we prefer to consider the quantity of 
sulphur in each acid as= 2, the oxygen com- 
bines with it in the following proportions: 
1; 2; 2.5; 3. 

Hyposulphuric acid is distinguished by the 
following properties: 

1st, It is decomposed by heat into sulphur- 
ous and sulphuric acids. 

2d, It forms soluble salts with baryta, 
strontia, lime, lead, and silver. 

3d, The hyposulphates are all soluble. 

4th, They yield sulphurous acid when their 
solutions are mixed with acids, only if the 
mixture becomes hot of itself, or be artificial- 
ly heated. 

5th, They disengage a great deal of sul- 
phurous acid at a high temperature, and are 
converted into neutral sulphates. 

Before quitting the acids of sulphur it 
deserves to be mentioned, that Dr Gules, of 
Paris, has, by means of a chest or case called 
Boe'te Fumigatoire, applied the vapour of 
burning sulphur, or sulphurous acid gas, 
mixed with air, to the surface of the body as 
an air bath, with great advantage in many 
chronic diseases of the skin, the joints, the 
glands, and the lymphatic system. See SALT. 



ACID 



108 



TARTARIC. 



ACID (TARTARIC). The casks in 
which some kinds of wine are kept become 
incrusted with a hard substance, tinged with 
the colouring matter of the wine, and other- 
wise impure, which has long been known by 
the name of argal, or tartar, and distinguish- 
ed into red and white, according to its colour. 
This being purified was termed cream, or 
crystals of tartar. It was afterwards disco- 
vered, that it consisted of a peculiar acid com- 
bined with potash ; and the supposition that 
it was formed during the fermentation of the 
wine was disproved by Boerhaave, Neuman, 
and others, who shewed that it existed ready 
formed in the juice of the grape. It has like- 
wise been found in other fruits, particularly 
before they are too ripe ; and in the tama- 
rind, sumac, balm, carduus benedictus, and 
the roots of restharrow, germander, and sage. 
The separation of tartaric acid from this aci- 
dulous salt is the first discovery of Scheele 
that is known. He saturated the superfluous 
acid, by adding chalk to a solution of the 
supertartrate in boiling water as long as any 
effervescence ensued, and expelled the acid 
from the precipitated tartrate of lime by 
means of the sulphuric. Or four parts of 
tartar may be boiled in twenty or twenty- 
four of water, and one part of sulphuric acid 
added gradually. By continuing the boiling, 
the sulphate of potash will fall down. When 
the liquor is reduced one-half, it is to be fil- 
tered ; and if any more sulphate be deposited 
by continuing the boiling, the filtering must 
be repeated. When no more is thrown 
down, the liquor is to be evaporated to the 
consistence of a syrup ; and thus crystals 
of impure tartaric acid, equal to half the 
weight of the tartar employed, will be ob- 
tained. 

Tartaric acid may be procured by careful 
evaporation in large crystals, which, when 
insulated, are found to be hexaedral prisms, 
with faces parallel, two and two. The four 
angles which are most obtuse are equal to 
one another, measuring each 129 ; the two 
remaining ones are also equal, and measure 
102. The prism is terminated by a three- 
sided pyramid, the inclinations of whose faces 
are 102.5, 122, and 125. The prisms are 
sometimes much compressed in a direction 
parallel to the axis. This takes place when 
the acid has been very slowly crystallized by 
evaporating a solution of it. Its taste is very 
acid and agreeable, so that it may supply the 
place of lemon-juice. It is very soluble in 
water. Burnt in an open fire, it leaves a 
coaly residuum ; in close vessels it gives out 
carbonic acid and carburetted hydrogen gas. 
By distilling nitric acid off the crystals, they 
may be converted into oxalic acid, and the 
nitric acid passes to the state of nitrous. 

To extract the whole acid from tartar, M. 
Thenard recommends, after saturating the 
redundant acid with chalk, to add muriate of 



lime to the supernatant neutral tartrate, by 
which means it is completely decomposed. 
The insoluble tartrate of lime being washed 
with abundance of water, is then to be treat- 
ed with three-fifths of its weight of strong 
sulphuric acid, diluted previously with five 
parts of water. But Fourcroy's process, as 
improved by Vauquelin, seems cheaper. Tar- 
tar is treated with quicklime and boiling water 
in the proportion, by the theory of equiva- 
lents, of 1 00 of tartar to 30 of dry lime, or 
40 of the slaked. A caustic magma is ob- 
tained, which must be evaporated to dryness, 
and gently heated. On digesting this in 
water, a solution of caustic potash is obtained, 
while tartrate of lime remains ; from which 
the acid may be separated by the equivalent 
quantity of oil of vitriol. 

According to Berzelius, tartaric acid is a 
compound of 3.807 hydrogen -f. 35.980 car- 
bon + 60.213 oxygen =100: to which re- 
sult he shews that of MM. Gay Lussac and 
Thenard to correspond, when allowance is 
made for a certain portion of water which 
they had omitted to estimate. The analysis 
of tartrate of lead gives 8.384 for the acid 
prime equivalent ; and it may be made up of 

3 hydrogen = 0.375 4.48 

4 carbon = 3.000 35.82 

5 oxygen == 5.000 59.70 

^^ _ . _ ^ 

8.375 100.00 

The crystallized acid is a compound of 8.375 
acid -f 1. 125 water = 9.5; or in 100 parts, 
88. 15 acid + 11.85 water. 

The prime equivalent of tartaric acid in 
crystals is, by my results, 9.25; and it seems 
made up of carbon 4 atoms =. 3 -f- hydrogen 
2 atoms = 0.25 -|- oxygen 6 = 6 ; or of car- 
bon 4 atoms, oxygen 4 atoms, and water 2. 
These atoms of water enter into dry tartrate 
of lead ; and hence the crystals of acid con- 
tain no water unessential to their constitution. 
Phil Trans. 1822. 

M. Rose has shewn, that tartaric acid has 
a peculiar influence in several cases of che- 
mical analysis. When a solution of red oxide 
of iron is mixed with tartaric acid, the oxide 
can be precipitated neither by caustic alkalis 
nor by their carbonates or succinates ; but 
tincture of galls, triple prussiate of potash, 
and alkaline hydrosulphurets, shew the pre- 
sence of iron in such a solution. The same 
thing is true of the oxides of titanium, man- 
ganese, cerium, yttrium, cobalt, and nickel, 
as well as with alumina and magnesia. So- 
lution of protosulphate of iron with tartaric 
acid is merely rendered intensely green by 
ammonia, and changes after long standing in 
the air to a yellow-coloured solution, which 
contains iron. 

The oxide of lead likewise is not separable 
by alkalis, when its solution has been treated 
with so much nitric acid that no tartrate of 
lead can precipitate. Oxides of tin and cop- 



ACID 



109 



TARTARIC. 



per fall under the same head. Lastly, oxide 
of antimony, when its solution in an acid is 
mixed with the tartaric, resists both alkalis 
and the most copious dilution with water. 
Thus, oxide of bismuth may be separated 
from oxide of antimony ; for the former re- 
sists the influence of tartaric acid. Muriate 
of platinum, the oxides of silver, zinc, and 
uranium, are not altered by tartaric acid. 
Gilbert's Ann. Ixxiii. 74. 

The tartrates, in their decomposition by 
fire, comport themselves like all the other 
vegetable salts, except that those with excess 
of acid yield the smell of carowie/ when heat- 
ed, and afford a certain quantity of the pyro- 
tartaric acid. All the soluble neutral tar- 
trates form, with tartaric acid, bitartrates of 
sparing solubility ; while all the insoluble 
tartrates may be dissolved in an excess of 
their acid. Hence, by pouring gradually an 
excess of acid into baryta, strontia, and lime 
waters, the precipitates formed at first cannot 
fail to disappear ; while those obtained by an 
excess of the same acid, added to concen- 
trated solutions of potash, soda, or ammonia, 
and the neutral tartrates of these bases as well 
as of magnesia and copper, must be perma- 
nent. The first are always flocculent ; the 
second always crystalline ; that of copper 
alone, is in a greenish-white powder. It 
likewise follows, that the greater number of 
acids ought to disturb the solutions of the 
alkaline neutral tartrates, because they trans- 
form these salts into bitartrates ; and, on the 
contrary, they ought to affect the solution of 
the neutral insoluble tartrates, which indeed 
always happens, unless the acid cannot dis- 
solve the base of the tartrate. The order of 
apparent affinities of tartaric acid are, lime, 
baryta, strontia, potash, soda, ammonia, and 
magnesia. 

The tartrates of potash, soda, and ammo- 
nia, are not only susceptible of combining to- 
gether, but also with the other tartrates, so as 
to form double or triple salts. We may thus 
easily conceive why the tartrates of potash, 
soda, and ammonia, do not disturb the so- 
lutions of iron and manganese ; and on the 
other hand, disturb the solutions of the salts of 
baryta, strontia, lime, and lead. In the first 
case, double salts are formed, however small 
a quantity of tartrate shall have been em- 
ployed; in the second, no double salt is 
formed, unless the tartrate be added in very 
great excess. 

The tartrates of lime and baryta are white, 
pulverulent, and insoluble. 

Tartrate of strontia, formed by the double 
decomposition of muriate of strontia and 
tartrate of potash, according to Vauquelin, is 
soluble, crystallizable, and consists of 52.88 
strontia and 47.12 acid. 

That of magnesia forms a gelatinous or 
gummy mass. 

Tartrate of potash, formerly called soluble- 



tartar, because much more so than the super- 
tartrate, crystallizes in oblong squares, bevel- 
led at the extremities. It has a bitterish 
taste, and is decomposed by heat, as its solu- 
tion is even by standing some time. It is 
used as a mild purgative. 

The supertartrate of potash, already men- 
tioned at the beginning of this article, is 
much used as a cooling and gently opening 
medicine, as well as in several chemical and 
pharmaceutical preparations. Mixed with an 
equal weight of nitre, and projected into a 
red-hot crucible, it detonates, and forms the 
white flux ; treated in the same way with 
half its weight of nitre, it forms the black 
flux ; and simply mixed with nitre in various 
proportions, it is called raw flux. It is like- 
wise used in dyeing, in hat-making, in gild- 
ing, and in other arts. 

The blanching of the crude tartar is aided 
by boiling its solution with l-20th of pipe 
clay. 

According to the analysis of Berzelius, it 
consists of 70.45 acid -}- 24.8 potash + 4.75 
water = 100; or 

. 2 primes acid, =16.75 70.30 
1 potash, = 5.95 24.95 

1 water, = 1.125 4.75 

23.825 100.00 

60 parts of water dissolve 4 of bitartrate at a 
boiling heat, and only 1 at 60 Fahr. It is 
quite insoluble in alcohol. It becomes very 
soluble in water, by adding to it one-fifth of 
its weight of borax, or even by the addition 
of boracic acid. It appears by Berzelius, that 
neutral tartrate of potash, dried in the sun, 
differs from the bitartrate, in containing no 
water of crystallization. He states it to be 
a compound of 58.69 acid -\- 41.31 potash = 
100; which afford 155.7 tartrate of lead. 
Now, 8.375: 5.95 :: 58.5 : 41.5, which are 
the equivalent proportions. 

On considering the great solvent property 
of cream of tartar, and that it is even capable 
of dissolving various oxides which are inso- 
luble in tartaric acid, as the protoxide of an- 
timony, M. Gay Lussac has recommended it 
as a useful agent in chemical analysis. He 
thinks that in many cases it acts the part of 
a single acid. According to this view, tartar 
emetic would be a compound of the cream 
tartar acid and protoxide of antimony. 
Creani of tartar generally contains from 3 to 
5 per cent of tartrate of lime, which are in a 
great measure separated when 3 parts of tar- 
tar are boiled with 1 of borax for a few mi- 
nutes in a sufficient quantity of water. The 
soluble cream of tartar which is obtained by 
this process is deliquescent ; it dissolves in 
its own weight of cold water at 54.5, and 
in half its weight of boiling water. Its solu- 
tion is very imperfectly decomposed by the 
sulphuric, nitric, and muriatic acids. 4 parts 
of tartar and 1 of boracic acid form a perma- 



ACID 



110 



TUNGSTIC. 



nent saline compound, very soluble in wa- 
ter. Alum also increases the solubility of 
tartar. 

By saturating the superfluous acid in this 
supertartrate with soda, a triple salt is form- 
ed, which crystallizes in large regular prisms 
of eight nearly equal sides, of a bitter taste, 
efflorescent, and soluble in about five parts of 
water. It consists, according to Vauquelin, 
of 54 parts tartrate of potash and 4-6 tartrate 
of soda ; and was once in much repute as a 
purgative by the name of Rochelle Salt or 
Sel de Seignette. 

The tartrate of soda is much less soluble 
than this triple salt, and crystallizes in slen- 
der needles or thin plates. 

The tartrate of ammonia is a very soluble 
bitter salt, and crystallizes easily. Its solu- 
tion is spontaneously decomposable. 

This too forms, with tartrate of potash, a 
triple salt, the solution of which yields, by 
cooling, fine pyramidal or prismatic efflores- 
cent crystals. Though both the neutral salts 
that compose it are bitter, this is not, but has 
a cooling taste. See SALT. 

M. Fabroni says, that sulphuric acid being 
mixed with three parts of boiling water, and 
cream of tartar in excess, gives a fluid which, 
after being evaporated, cooled, and allowed 
to deposit undecomposed tartar, sulphate of 
potash, &c. will not furnish any other de- 
posit, and resembles oil in its appearance. 
When further evaporated to the consistence 
of syrup, and again cooled, it solidifies in a 
mass composed of imperfect prismatic crys- 
tals, which when dry have something the 
appearance of camphor. It dissolves rapidly 
in water, but in alcohol yields its tartaric 
acid, while acid sulphate of potash is left. 
On analysis it gave 72 tartaric acid, and 28 
sulphate of potash. Gior. de Fisica, vi. 452. 

ACID (TITANIC). By fusing powder- 
ed rutilite with thrice its weight of carbonate 
of potash, dissolving the compound in mu- 
riatic acid, precipitating by caustic ammonia, 
digesting the precipitate for a certain time 
with hydrosulphuret of ammonia, and then 
digesting the solid matter left in weak mu- 
riatic acid, M. Rose obtains a perfectly white 
oxide of titanium, which is not attacked by 
acids, but which becomes red by touching 
moistened litmus. As it acts with alkalis 
precisely as an acid, M. Rose calls it titanic 
acid. 

He has more recently given the following 
process for obtaining titanic acid. Pulverize 
and wash menachanite, heat it highly in a 
porcelain tube, and pass dry sulphuretted 
hydrogen gas over it ; the oxide of iron will 
become sulphuret, the titanic acid will re- 
main unchanged. When cold, digest the 
product in strong muriatic acid ; sulphuret- 
ted hydrogen will be cooled, and the titanic 
acid, rendered insoluble by the heat, and 



coloured grey by the sulphur, will remain. 
It is to be washed, and heated red hot, to 
drive off the sulphur. 

One operation is not sufficient to free the 
titanic acid perfectly from iron ; the product 
is therefore again to be heated in a tube 
through which sulphuretted hydrogen is 
passing, and then treated as before ; when 
again washed and heated red hot, it becomes 
perfectly white and pure. 

The operation may be shortened by heat- 
ing the titaniferous iron with sulphur in a 
crucible, and then acting by concentrated 
muriatic acid : but in this first operation as 
much iron remains with the titanic acid as 
exists in rutilite ; then an operation with sul- 
phuretted hydrogen renders the substance 
perfectly pure. 

It is said to consist of titanium, 66.05 

oxygen, 33.95 ; 

whence, if, like the other metallic acids, this 
be supposed to contain 3 atoms of oxygen, 
the atomic weight of the metal will be 5.83, 
or possibly 6. 

Acid titanate of potash consists of 



100. 



titanic acid, - 82.33 
potash, - - 17.77{ 
Acid titanate of soda of 

titanic acid, - 83.15J lnn 
soda, - - 16.85 I 100 ' 
Sulphotitanic acid consists of 

titanic acid, - 76.67 ^ 
sulphuric acid, - 7.67 100. 
water, - - 15.663 
Oxalo-titanic acid, of titanic acid 74.1, 
oxalic acid 10.4, water 15.5. 

Sulphuret of titanium consists of titanium 
49. 17, sulphur 50.83. 

Protochloride of titanium consists of tita- 
nium 6, chlorine 3.6. 

Perchloride of titanium consists of titani- 
um 6.66, chlorine 7.94. 

Annales de Chim. xxiii. 353. Annals of 

Phil N. S. ix. 18. 

ACID (TUNGSTIC) has been found 
only in two minerals ; one of which, former- 
ly called tungsten, is a tungstate of lime, 
and is very rare ; the other, more common, 
is composed of tungstic acid, oxide of iron, 
and a little oxide of manganese. The acid 
is separated from the latter in the following 
way. The wolfram cleared from its siliceous 
gangue, and pulverized, is heated in a mat- 
rass with five or six times its weight of mu- 
riatic acid, for half an hour. The oxides of 
iron and manganese being thus dissolved, 
we obtain the tungstic acid under the form 
of a yellow powder. After washing it re- 
peatedly with water, it is then digested in an 
excess of liquid ammonia heated, which dis- 
solves it completely. The liquor is filtered 
and evaporated to dryness in a capsule. 
The dry residue being ignited, the ammonia 
flies off, and pure tungstic acid remains. If 



ACONITA. 



Ill 



ACTINOLITE. 



the whole of the wolfram has not been de- 
composed in this operation, it must be sub- 
jected to the muriatic acid again. , 

It is tasteless, and does not affect vegetable 
colours. The tungstates of the alkalis and 
magnesia are soluble and crystal lizable ; the 
other earthy ones are insoluble, as well as 
those of the metallic oxides. The acid is 
composed of 100 parts metallic tungsten, 
and 25 or 26.4 oxygen. 

ACID (TUNGSTOUS). What has been 
thus called appears to be an oxide of tung- 
sten. 

ACID (URIC). The same with LITHIC 
ACID ; which see. 

ACID (VEGETO-SULPHURIC) 

This compound was obtained by M. Bra- 
connot, in treating ligneous fibre with sul- 
phuric acid. It consists of sulphur, carbon, 
hydrogen, and oxygen, or of a vegetable 
matter and the elements of sulphuric acid, 
but in proportions unknown. 

ACID (XANTHIC). See ACID (HY- 

DROXANTHIC). 

ACID (ZOONIC). In the liquid pro- 
cured by distillation from animal substances, 
which had been supposed to contain only 
carbonate of ammonia and an oil, Berthollet 
imagined he had discovered a peculiar acid, 
to which he gave the name of zoonic. The- 
nard, however, has demonstrated, that it is 
merely acetic acid combined with animal 
matter. 

ACIDIFIABLE. Capable of being 
converted into an acid by an acidifying prin- 
ciple. (See ACID.) Substances possessing 
this property are called radicals or acidifia- 
l)le bases. 

ACIDIFYING PRINCIPLE. See re- 
marks on this subject, in the general article 
ACID. 

ACIDIMETRY. The measurement of 
the strength of acids. This is effected by 
saturating a given weight of them with an 
alkaline base ; the quantity of which requi- 
site for the purpose is the measure of their 
power. 

ACIDULE. A term applied by the 
French chemists to those salts in which the 
base is combined with such an excess of 
acid, that they manifestly exhibit acid pro- 
perties ; such as the supertartrate of potash. 

ACONITA. A poisonous vegetable prin- 
ciple, probably alkaline, supposed to exist in 
the aconitum napellus, or wolfsbane. In 
some British journals it is stated that M. 
Brandes had procured this alkaline principle. 
But I observe in his translation of my Dic- 
tionary into the German language, that he 
refers the point to the researches of M. Pes- 
chier of Geneva, who has not hitherto made 
it distinctly out. Bucholz analyzed the herb 
aconite, and found the following constituents 
in 20 ounces : 



oz. dr. gr. 

Water and volatile matter, 16 6 
Fibrous matter, 130 

Green resin, - 1 50 

Vegetable albumen (Pflanze- 

neiweiss), - - 03 55 
Extractive, with various ace- 
tates and muriates, - 4 50 
Gummy matter, 060 

Malate and citrate of lime, 1 56 

20 2 30 

The distilled water of aconite, though 
smelling rank of the plant, is not poisonous. 
The noxious principle is therefore not vola- 
tile. The details of the analysis have not 
reached this country. 

ACROSPIRE. The plumula is that part 
of the embryon of a plant destined to become 
the stem, and which bears the cotylidons. 
According to Grew, the acrospire is the plu- 
mula of barley developed by germination. It 
is sometimes named plantula. 

ACTINOLITE. Strahhtein of Werner. 
Amphibole Actinote hexaedre of Hauy. 
There are three varieties of this mineral ; the 
crystallized, the asbestous, and the glassy. 

1st, Crystallized actinolite. Colour leek- 
green, and green of darker shades. It crys- 
tallizes in long oblique hexaedral prisms, 
with irregular terminations. Crystals fre- 
quently striated lengthwise, sometimes acicu- 
lar. Its lustre is shining. It is translucent. 
Occasionally it is found in silky fibres. Its 
sp. gr. varies from 3.0 to 3.3. Fracture 
usually radiated ; sometimes it is foliated 
with an indistinct twofold cleavage. It 
scratches glass. 

2d, Asbestous actinolite. Colours green, 
verging on grey and brown, and smalt-blue. 
Massive, and in elastic capillary crystals, 
which are grouped in wedge-shaped, radi- 
ated, or promiscuous masses. Internal lus- 
tre pearly. Melts before the blow-pipe into 
a dark glass. Fracture intermediate between 
fibrous and narrow radiated. Fragments 
wedge-shaped. Opaque. Soft. Tough but 
sectile. Sp. gr. 2.7 to 2.9. 

3d, Glassy actinolite. Colours, mountain- 
green, and emerald-green. In thin six-vsided 
needle-form crystals. Has cross rents. Sp. 
gr. from 3.0 to 3.2. The composition of 
actinolite is very differently stated by diffe- 
rent analysts. Laugier's results with glassy 
actinolite are the following, and they approxi- 
mate to those of Vauquelin on asbestous ac- 
tinolite; silica 50, lime 9.75, magnesia 19.25, 
oxide of iron 11, alumina 0.75, oxide of man- 
ganese 0.5, oxide of chromium 3, potash 0.5, 
moisture 5, loss 0.25. 28.2 of alumina and 
3.84 of tungstic acid were found in 100 parts 
of asbestous actinolite from Cornwall. 

Actinolite is found chiefly in primitive dis- 
tricts with a magnesian basis. It accompa- 
nies talc, and some micaceous rocks. Its 



ADIPOCERE. 



112 



ADIPOCERE. 



principal localities are Zillerthal in the Ty- 
rol, Mont St Gothard, near Saltzburg in 
Saxony, in Norway, and in Piedmont. In 
Great Britain, it is found in Cornwall and 
Wales ; and in Glen Elg, the isles of Lewis 
and Sky. It is never found in secondary 
mountains. 

ADAMANT. See DIAMOND. 
ADHESION. See COHESION. 
ADHESIVE SLATE. See SLATE. 
ADIPOCERE. The attention of che- 
mists has been much excited by the sponta- 
neous conversion of animal matter into a sub- 
stance considerably resembling spermaceti. 
The fact has long been well known, and is said 
to have been mentioned in the works of Lord 
Bacon, though I have not seen the passage. 
On the occasion of the removal of a very 
great number of human bodies from the an- 
cient burying-place Des Innocens at Paris, 
facts of this nature were observed in the 
most striking manner. Fourcroy may be 
called the scientific discoverer of this pecu- 
liar matter, as well as the saponaceous ammo- 
niacal substance contained in bodies aban- 
doned to spontaneous destruction in large 
masses. This chemist read a memoir on the 
subject in the year 1789 to the Royal Aca- 
demy of Sciences, from which I shall ab- 
stract the general contents. 

At the time of clearing the before men- 
tioned burying-place, certain philosophers 
were specially charged to direct the precau- 
tions requisite for securing the health of the 
workmen. A new and singular object of 
research presented itself, which had been 
necessarily unknown to preceding chemists. 
It was impossible to foretell what might be 
the contents of a soil overloaded for succes- 
sive ages with bodies resigned to the putre- 
factive process. This spot differed from 
common burying-grounds, where each indi- 
vidual object is surrounded by a portion of 
the soil. It was the burying-ground of a 
large district, wherein successive generations 
of the inhabitants had been deposited for up- 
wards of three centuries. It could not be 
foreseen that the entire decomposition might 
be retarded for more than forty years ; nei- 
ther was there any reason to suspect that any 
remarkable difference would arise from the 
singularity of situation. 

The remains of the human bodies im- 
mersed in this mass of putrescence were 
found in three different states, according to 
the time they had been buried, the place they 
occupied, and their relative situations with 
regard to each other. The most ancient 
were simply portions of bones, irregularly 
dispersed in the soil, which had been fre- 
quently disturbed. A second state, in cer- 
tain bodies which had always been insulated, 
exhibited the skin, the muscles, tendons, and 
aponeuroses, dry, brittle, hard, more or less 
grey, and similar to what are called mum- 



mies in certain caverns where this change 
has been observed, as in the catacombs *at 
Rome, and the vault of the Cordeliers at 
Tholouse. 

The third and most singular state of these 
soft parts was observed in the bodies which 
filled the common graves or repositories. By 
this appellation are understood cavities of 
thirty feet in depth, and twenty on each side, 
which were dug in the burying-ground of 
the Innocents, and were appropriated to con- 
tain the bodies of the poor; which were 
placed in very close rows, each in its pro- 
per wooden bier. The necessity for dispos- 
ing a great number, obliged the men charged 
with this employment to arrange them so 
near each other, that these cavities might be 
considered when filled as an entire mass of 
human bodies separated only by two planks 
of about half an inch thick. Each cavity 
contained between one thousand and fifteen 
hundred. When one common grave of this 
magnitude was filled, a covering of about 
one foot deep of earth was laid upon it, and 
another excavation of the same sort was 
made at some distance. Each grave re- 
mained open about three years, which was 
the time required to fill it. According to 
the urgency of circumstances, the graves 
were again made on the same spot after an 
interval of time, not less than fifteen years, 
nor more than thirty. Experience had taught 
the workmen, that this time was not suffi- 
cient for the entire destruction of the bodies, 
and had shewn them the progressive changes 
which form the object of M. Fourcroy's me- 
moir. 

The first of these large graves opened in 
the presence of this chemist, had been closed 
for fifteen years. The coffins were in good 
preservation, but a little settled, and the wood 
(I suppose deal) had a yellow tinge. When 
the covers of several were taken off, the bodies 
were observed at the bottom, leaving a con- 
siderable distance between their surface and 
the cover, and flattened as if they had suffered 
a strong compression. The linen which had 
covered them was slightly adherent to the 
bodies ; and, with the form of the different 
regions, exhibited, on removing the linen, 
nothing but irregular masses of a soft ductile 
matter of a grey-white colour. These masses 
environed the bones on all sides, which had no 
solidity, but broke by any sudden pressure. 
The appearance of this matter, its obvious 
composition and its softness, resembled com- 
mon white cheese ; and the resemblance was 
more striking from the print which the threads 
of the linen had made upon its surface. Tin's 
white substance yielded to the touch, and be- 
came soft when rubbed for a time between 
the fingers. 

No very offensive smell was emitted from 
these bodies. The novelty and singularity of 
the spectacle, and the example of the grave- 



ADIPOCERE. 



113 



ADIPOCERE. 



diggers, dispelled every idea cither of disgust 
or apprehension. These men asserted, that 
they never found this matter, by them called 
gras (fat), in bodies interred alone ; but that 
the accumulated bodies of the common graves 
only were subject to this change. On a very 
attentive examination of a number of bodies 
passed to this state, M. Fourcroy remarked 
that the conversion appeared in different stages 
of advancement, so that, in various bodies, the 
fibrous texture and colour, more or less red, 
were discernible within the fatty matter ; that 
the masses covering the bones were entirely of 
the same nature, offering indistinctly in all 
the regions a grey substance, for the most 
part soft and ductile, sometimes dry, always 
easy to be separated in porous fragments, pe- 
netrated with cavities, and no longer exhibit- 
ing any traces of membranes, muscles, ten- 
dons, vessels, or nerves. On the first inspec- 
tion of these white masses, it might have 
been concluded that they were simply the 
cellular tissue, the compartments and vesicles 
of which they very well represented. 

By examining this substance in the diffe- 
rent regions of the body, it was found that 
the skin is particularly disposed to this re- 
markable alteration. It was afterwards per- 
ceived that the ligaments and tendons no long- 
er existed, or at least had lost their tenacity ; 
so that the bones were entirely unsupported, 
and left to the action of their own weight ; 
whence their relative places were preserved 
in a certain degree by mere juxtaposition ; 
the least effort being sufficient to separate 
them. The grave-diggers availed themselves 
of this circumstance in the removal of the 
bodies ; for they rolled them up from head 
to foot, and by that means separated from 
each other the extremities of the bones, which 
had formerly been articulated. In all those 
bodies which were changed into the fatty mat- 
ter, the abdominal cavity had disappeared. 
The teguments and muscles of this region 
being converted into the white matter, like 
the other soft parts, had subsided upon the 
vertebral column, and were so flattened as to 
leave no place for the viscera ; and according- 
ly there was scarcely ever any trace observed 
in the almost obliterated cavity. This ob- 
servation was for a long time matter of asto- 
nishment to the investigators. In vain did 
they seek, in the greater number of bodies, 
the place and substance of the stomach, the 
intestines, the bladder, and even the liver, the 
spleen, the kidneys, and the matrix in females. 
All these viscera were confounded together, 
and for the most part no traces of them were 
left. Sometimes only certain irregular masses 
were found, of the same nature as the white 
matter, of different bulks, from that of a nut 
to two or three inches in diameter, in the re- 
gions of the liver or of the spleen. 

The thorax likewise offered an assemblage 
of facts no less singular and interesting. The 



external part of this cavity was flattened and 
compressed like the rest of the organs ; the 
ribs, spontaneously luxated in their articula- 
tions with the vertebrce, were settled upon the 
dorsal column ; their arched part left only a 
small space on each side between them and 
the vertebrae. The pleura, the mediastines, 
the large vessels, the aspera arteria, and even 
the lungs and the heart, were no longer dis- 
tinguishable ; but for the most part had en- 
tirely disappeared, and in their place nothing 
was seen but some parcels of the fatty sub- 
stance. In this case, the matter which was 
the product of decomposition of the viscera, 
charged with blood and various humours, 
differs from that of the surface of the body, 
and the long bones, in the red or brown 
colour possessed by the former. Sometimes 
the observers found in the thorax a mass ir- 
regularly rounded, of the same nature as the 
latter, which appeared to them to have arisen 
from the fat and fibrous substance of the 
heart. They supposed that this mass, not 
constantly found in all the subjects, owed its 
existence to a superabundance of fat in this 
viscus, where it was found. For the general 
observation presented itself, that, in similar 
circumstances, the fat parts undergo this 
conversion more evidently than the others, and 
afford a larger quantity of the white matter. 

The external region in females exhibited 
the glandular and adipose mass of the breasts 
converted into the fatty matter, very white 
and homogeneous. 

The head was, as has already been re- 
marked, environed with the fatty matter; 
the face was no longer distinguishable in the 
greatest number of subjects ; the mouth, dis- 
organized, exhibited neither tongue nor pa- 
late ; and the jaws, luxated and more or less 
displaced, were environed with irregular layers 
of the white matter. Some pieces of the same 
matter usually occupied the place of the parts 
situated in the mouth : the cartilages of the 
nose participated in the general alteration of 
the skin ; the orbits, instead of eyes, contained 
white masses ; the ears were equally disor- 
ganized ; and the hairy scalp, having under- 
gone a similar alteration to that of the other 
organs, still retained the hair. M. Fourcroy 
remarks incidentally, that the hair appears to 
resist every alteration much longer than any 
other part of the body. The cranium con- 
stantly contained the brain contracted in bulk ; 
blackish at the surface, and absolutely changed 
like the other organs. In a great number of 
subjects which were examined, this viscus was 
never found wanting, and it was always in the 
above-mentioned state : which proves that the 
substance of the brain is greatly disposed to 
be converted into the fat matter. 

Such was the state of the bodies found in 
the burial-ground Des Innocens. Its modi- 
fications were also various. Its consistence 
in bodies lately changed, that is to say, from 
H 



ADIPOCERE. 



ADIPOCERE. 



three to five years, was soft and very ductile, 
containing a great quantity of water. In 
other subjects converted into this matter for a 
long time, such as those which occupied the 
cavities which had been closed thirty or forty 
years, this matter is drier, more brittle, and 
in denser flakes. In several which were de- 
posited in dry earth, various portions of the 
fatty matter had become semitransparent. The 
aspect, the granulated texture, and brittleness 
of this dried matter, bore a considerable re- 
semblance to wax. 

The period of the formation of this sub- 
stance had likewise an influence on its pro- 
perties. In general, all that had been form- 
ed for a long time was white, uniform, and 
contained no foreign substance, or fibrous re- 
mains ; such, in particular, was that afforded 
by the skin of the extremities. On the con- 
trary, in bodies recently changed, the fatty 
matter was neither so uniform nor so pure as 
in the former ; but it was still found to con- 
tain portions of muscles, tendons, and liga- 
ments, the texture of which, though already 
altered and changed in its colour, was still 
distinguishable. Accordingly, as the conver- 
sion was more or less advanced, these fibrous 
remains were more or less penetrated with the 
fatty matter, interposed as it were between the 
interstices of the fibres. This observation 
shews, that it is not merely the fat which is 
thus changed, as was natural enough to think 
at first sight. Other facts confirm this asser- 
tion. The skin, as has been remarked, be- 
comes easily converted into very pure white 
matter, as does likewise the brain, neither of 
which has been considered by anatomists to be 
fat. It is true, nevertheless, that the unc- 
tuous parts, and bodies charged with fat, 
appear more easily and speedily to pass to the 
state under consideration. This was seen in 
the marrow which occupied the cavities of the 
longer bones. And again, it is not to be sup- 
posed but that the greater part of these bodies 
had been emaciated by the illness which ter- 
minated their lives ; notwithstanding which, 
they were all absolutely turned into this fatty 
substance. 

An experiment made by M. Poulletier de 
la Salle and Fourcroy likewise evinced, that 
a conversion does not take place in the fat 
alone. M. Poulletier had suspended in his 
laboratory a small piece of the human liver, 
to observe what would arise to it by the con- 
tact of the air. It partly putrefied, without, 
however, emitting any very noisome smell. 
Larva? of the dermestes and bruchus attacked 
and penetrated it in various directions : at last 
it became dry, and after more than ten years' 
suspension, it was converted into a white 
friable substance resembling dried agaric, 
which might have been taken for an earthy 
substance. In this state it had no perceptible 
smell. M. Poulletier was desirous of know- 
ing the state of this animal matter, and experi- 



ment soon convinced him and M. F. that it 
was very far from being in the state of an 
earth. It melted by heat, and exhaled in the 
form of vapour, which had the smell of a very 
fetid fat : spirit of wine separated a concres- 
cible oil, which appeared to possess all the 
properties of spermaceti. Each of the three 
alkalis converted it into soap ; and, in a word, 
it exhibited all the properties of the fatty 
matter in the burial-ground of the Innocents 
exposed for several months to the air. Here 
then was a glandular organ, which in the 
midst of the atmosphere had undergone a 
change similar to that of the bodies in the 
burying-place ; and this fact sufficiently 
shows, that an animal substance, which is 
very far from being of the nature of grease, 
may be totally converted into this fatty sub- 
stance. 

Among the modifications of this remark- 
able substance in the burying-ground before 
mentioned, it was observed that the dry, 
friable, and brittle matter, was most com- 
monly found near the surface of the earth, 
and the soft ductile matter at a greater depth. 
M. Fourcroy remarks, that this dry matter did 
not differ from the other merely in containing 
less water, but likewise by the volatilization 
of one of its principles. 

The grave-diggers assert, that near three 
years are required to convert a body into this 
fatty substance. But Dr Gibbes of Oxford 
found, that lean beef secured in a running 
stream was converted into this fatty matter at 
the end of a month. He judges from facts, 
that running water is most favourable to this 
process. He took three lean pieces of mut- 
ton, and poured on each a quantity of the 
three common mineral acids. At the end of 
three days, each was much changed : that in 
the nitric acid was very soft, and converted 
into the fatty matter ; that in the muriatic 
acid was. not in that time so much altered ; 
the sulphuric acid had turned the other black. 
M. Lavoisier thinks that this process may 
hereafter prove of great use in society. It 
is not easy to point out what animal sub- 
stance, or what situation, might be the best 
adapted for an undertaking of this kind. M. 
L. points out fecal matters ; but I have not 
heard of any conversion having taken place 
in these animal remains, similar to that of the 
foregoing. 

The result of M. Fourcroy 's inquiries into 
the ordinary changes of bodies recently de- 
posited in the earth, was not very extensive. 
The grave-diggers informed him, that those 
bodies interred do not perceptibly change 
colour for the first seven or eight days; that 
the putrid process disengages elastic fluid, 
which inflates the abdomen, and at length 
bursts it; that this event instantly causes 
vertigo, faintness and nausea, in such persons 
as unfortunately are within a certain distance 
of the scene where it takes place ; but that 



ADIPOCERE. 



115 



ADIPOCERE. 



when the object of its action is nearer, a sud- 
den privation of sense, and frequently death, 
is the consequence. These men are taught 
by experience, that no immediate danger is to 
be feared from the disgusting business they 
are engaged in, excepting at this period, which 
they regard with the utmost terror. They re- 
sisted every inducement and persuasion which 
these philosphers made use of, to prevail on 
them to assist their researches into the nature 
of this active and pernicious vapour. M. 
Fourcroy takes occasion from these facts, as 
well as from the pallid and unwholesome 
appearance of the grave-diggers, to reprobate 
burials in great towns or their vicinity. 

Such bodies as are interred alone, in the 
midst of a great quantity of humid earth, are 
totally destroyed by passing through the suc- 
cessive degrees of the ordinary putrefaction ; 
and this destruction is more speedy, the 
warmer the temperature. But if these in- 
sulated bodies be dry and emaciated ; if the 
place of deposition be likewise dry, and the 
locality and other circumstances such, that 
the earth, so far from receiving moisture from 
the atmosphere, becomes still more effectually 
parched by the solar rays, the animal juices 
are volatilized and absorbed, the solids con- 
tract and harden, and a peculiar species of 
mummy is produced. But every circum- 
stance is very different in the common bury- 
ing-grounds. Heaped together almost in 
contact, the influence of external bodies af- 
fects them scarcely at all, and they become 
abandoned to a peculiar disorganization, 
which destroys their texture, and produces 
the new and most permanent state of combi- 
nation here described. From various obser- 
vations, which I do not here extract, it was 
found, that this fatty matter was capable of 
enduring in these burying-places for thirty 
or forty years, and is at length corroded and 
carried off by the aqueous putrid humidity 
which there abounds. 

Among other interesting facts afforded by 
the chemical examination of this substance, 
are the following, from experiments by M. 
Fourcroy. 

1. Tin's substance is fused at a less degree 
of heat than that of boiling water, and may 
be purified by pressure through a cloth, which 
disengages a portion of fibrous and bony mat- 
ter. 2t The process of destructive distillation 
by a very graduated heat was begun, but not 
completed on account of its tediousness, and 
the little promise of advantage it afforded. 
The products which came over were water 
charged with volatile alkali, a fat oil, concrete 
volatile alkali, and no elastic fluid during the 
time the operation was continued. 3. Frag- 
ments of the fatty matter exposed to the air 
during the hot and dry summer of 1786, be- 
came dry, brittle, and almost pulverulent at 
the surface. On a careful examination, cer- 
tain portions were observed to be semitrans- 



parent, and more brittle than the rest. These 
possessed all the apparent properties of wax, 
and did not afford volatile alkali by distilla- 
tion. 4*. With water this fatty matter exhi- 
bited all the appearances of soap, and afford- 
ed a strong lather. The dried substance did 
not form the saponaceous combination with 
the same facility or perfection as that which 
was recent. About two-thirds of this dried 
matter separated from the water by cooling, 
and proved to be the semitransparent sub- 
stance resembling wax. This was taken 
from the surface of the soapy liquor, which 
being then passed through the filter, left a 
white soft shining matter, which was fusible 
and combustible. 5. Attempts were made 
to ascertain the quantity of volatile alkali in 
this substance, by the application of lime, 
and of the fixed alkalis, but without success ; 
for it was difficult to collect and appreciate 
the first portions which escaped, and likewise 
to disengage the last portions. The caustic 
volatile alkali, with the assistance of a gentle 
heat, dissolved the fatty matter, and the solu- 
tion became perfectly clear and transparent 
at the boiling temperature of the mixture, 
which was 185 F. 6. Sulphuric acid, of 
the specific gravity of 2.0, was poured upon 
six times its weight of the fatty matter, and 
mixed by agitation. Heat was produced, and 
a gas or effluvium of the most insupportable 
putrescence was emitted, which infected the 
air of an extensive laboratory for several days. 
M. Fourcroy says, that the smell cannot be 
described, but that it is one of the most horrid 
and repulsive that can be imagined. It did 
not, however, produce any indisposition either 
in himself or his assistants. By dilution with 
water, and the ordinary processes of evapora- 
tion and cooling, properly repeated, the sul- 
phates of ammonia and of lime were obtain- 
ed. A substance was separated from the 
liquor, which appeared to be the waxy mat- 
ter, somewhat altered by the action of the 
acid. 7. The nitrous and muriatic acids 
were also applied, and afforded phenomena 
worthy of remark, but which for the sake of 
conciseness are here omitted. 8. Alcohol 
does not act on this matter at the ordinary 
temperature of the air. But by boiling it 
dissolves one- third of its own weight, which 
is almost totally separable by cooling as low 
as 55. The alcohol, after this process, 
affords by evaporation a portion of that waxy 
matter which is separable by acids, and is 
therefore the only portion soluble in cold al- 
cohol. The quantity of fatty matter operated 
on was 4 ounces, or 2304 grains, of which 
the boiling spirit took up the whole except 
26 grains, which proved to be a mixture of 
20 grains of ammoniacal soap, and 6 or 8 
grains of the phosphates of soda and lime. 
From this experiment, which was three times 
repeated with similar results, it appears that 
alcohol is well suited to afford an analysis of 



ADIPOCERE. 



116 



ADIPOCERE. 



the fatty matter. It does not dissolve the 
neutral salts: when cold, it dissolves that 
portion of concrete animal oil from which 
the volatile alkali had flown off; and when 
heated, it dissolves the whole of the truly 
saponaceous matter, which is afterwards com- 
pletely separated by cooling. And accord- 
ingly it was found, that a thin plate of the 
fatty matter, which had lost nearly the whole 
of its volatile alkali by exposure to the air 
for three years, was almost totally dissolved 
by the cold alcohol. 

The concrete oily or waxy substance ob- 
tained in these experiments constitutes the 
leading object of research, as being the pecu- 
liar substance with which the other well 
known matters are combined. It separates 
spontaneously by the action of the air, as well 
as by that of acids. These last separate it in 
a state of greater purity, the less disposed the 
acid may be to operate in the way of com- 
bustion. It is requisite, therefore, for this 
purpose, that the fatty matter should be pre- 
viously diffused in 12 times its weight of hot 
water; and the muriatic or acetous acid is 
preferable to the sulphuric or nitrous. The 
colour of the waxy matter is greyish ; and 
though exposure to the air, and also the ac- 
tion of the oxygenated muriatic acid, pro- 
duced an apparent whiteness, it nevertheless 
disappeared by subsequent fusion. No me- 
thod was discovered by which it could be 
permanently bleached. 

The nature of this wax or fat is different 
from that of any other known substance of 
the like kind. When slowly cooled after fu- 
sion, its texture appears crystalline or shivery, 
like spermaceti ; but a speedy cooling gives 
it a semi transparency resembling wax. Upon 
the whole, nevertheless, it seems to approach 
more nearly to the former than to the latter 
of these bodies. It has less smell than sper- 
maceti, and melts at 127 F. ; Dr Bostock 
says 92. Spermaceti requires 6 more of heat 
to fuse it, (according to Dr Bostock 20). 
The spermaceti did not so speedily become 
brittle by cooling as the adipocere. One 
ounce of alcohol, of the strength between 39 
and 40 degrees of Baume's aerometer, dis- 
solved when boiling hot 1 2 gros of this sub- 
stance ; but the same quantity in like circum- 
stances dissolved only 30 or 36 grains of 
spermaceti. The separation of these matters 
was also remarkably different, the spermaceti 
being more speedily deposited, and in a 
much more regular and crystalline form. 
Ammonia dissolves it with singular facility, 
and even in the cold, this concrete oil separates 
from the fatty matter ; and by heat it forms 
a transparent solution, which is a true soap. 
But no excess of ammonia can produce such 
an effect with spermaceti. 

M. Fourcroy concludes his memoir with 
some speculations on the change to which 
animal substances in peculiar circumstances 



are subject. In the modern chemistry, soft 
animal matters are considered as a composi- 
tion of the oxides of hydrogen and carbonated 
azote, more complicated than those of vege- 
table matters, and therefore more incessantly 
tending to alteration. If then the carbon be 
conceived to unite with the oxygen, either of 
the water which is present, or of the other 
animal matters, and thus escape in large 
quantities in the form of carbonic acid gas, 
we shall perceive the reason why this con- 
version is attended with so great a loss of 
weight, namely, about nine-tenths of the 
whole. The azote, a principle so abundant 
in animal matters, will form ammonia by 
combining with the hydrogen ; part of this 
will escape in the vaporous form, and the rest 
will remain fixed in the fatty matter. The 
residue of the animal matters, deprived of a 
great part of their carbon, of their oxygen, 
and the whole of their azote, will consist of 
a much greater proportion of hydrogen, to- 
gether with carbon and a minute quantity of 
oxygen. This, according to the theory of 
M. Fourcroy, constitutes the waxy matter, 
or adipocere, which, in combination with 
ammonia, forms the animal soap into which 
the dead bodies are thus converted. 

Muscular fibre, macerated in dilute nitric 
acid, and afterwards well washed in warm 
water, affords pure adipocere, of a light yel- 
low colour, nearly of the consistence of tal- 
low, of a homogenous texture, and of course 
free from ammonia. This is the mode in 
which it is now commonly procured for che- 
mical experiment. 

This curious substance has been more re- 
cently examined by Chevreul. He found it 
composed of a small quantity of ammonia, 
potash, and lime, united to much margarine, 
and to a very little of another fatty matter dif- 
ferent from that. Weak muriatic acid seize* 
the three alkaline bases. On treating the 
residue with a solution of potash, the marga- 
rine is precipitated in the form of a pearly 
substance, while the other fat remains dis- 
solved. Fourcroy being of opinion that the 
fatty matter of animal carcasses, the sub- 
stance of biliary calculi, and spermaceti, were 
nearly identical, gave them the same name 
of adipocere; but it appears from the re- 
searches of M. Chevreul, that these substan- 
ces are very different from each other. 

In the Philosophical Transactions for 1813 
there is a very interesting paper on the above 
subject, by Sir E, Home and Mr Brande. 
He adduces many curious facts to prove that 
adipocere is formed by an incipient and in- 
complete putrefaction. Mary Howard, aged 
44-, died on the 12th May 1790, and was 
buried in a grave ten feet deep, at the east 
end of Shoreditch church-yard, ten feet to 
the east of the great common sewer, which 
runs from north to south, and has always a 
current of water in it, the usual level of which 



ADIPOCERE. 



117 



AEROSTATION. 



is eight feet below the level of the ground, 
and two feet above the level of the coffins in 
the graves. In August 1811 the body was 
taken up, with some others buried near it, 
for the purpose of building a vault, and the 
flesh in all of them was converted into adi- 
pocere or spermaceti. At the full and new 
moon the tide raises water into the graves, 
which at other times are dry. To explain 
the extraordinary quantities of fat or adipo- 
cere formed by animals of a certain intestinal 
construction, Sir E. observes, that the current 
of water which passes through their colon, 
while the loculated lateral parts are full of 
solid matter, places the solid contents in 
somewhat similar circumstances to dead bo- 
dies in the banks of a common sewer. 

The circumstance of ambergris, which con- 
tains 60 per cent of fat, being found in im- 
mense quantities in the lower intestines of the 
spermaceti whales, and never higher up than 
seven feet from the anus, is an undeniable 
proof of fat being formed in the intestines; 
and as ambergris is only met with in whales 
out of health, it is most probably collected 
there from the absorbents, under the influence 
of disease, not acting so as to take it into the 
constitution. In the human colon, solid 
masses of fat are sometimes met with in a 
diseased state of that canal, and are called 
scybala. A description and analysis by me 
of a mass of ambergris, extracted in Perth- 
shire from the rectum of a living woman, 
were published in a London Medical Journal 
in September 1817. There is a case com- 
municated by Dr Babington, of fat formed 
in the intestines of a girl four and a half 
years old, and passing off by stool. Mr 
Brande found, on the suggestion of Sir E. 
Home, that muscle digested in bile is con- 
vertible into fat at the temperature of about 
100. If the substance, however, pass ra- 
pidly into putrefaction, no fat is formed. 
Faeces voided by a gouty gentleman after six 
day's constipation, yielded, on infusion in 
water, a fatty film. This process of forming 
fat in the lower intestines by means of bile, 
throws considerable light upon the nourish- 
ment derived from clysters, a fact well as- 
certained, but which could not be explained. 
It also accounts for the wasting of the body 
which so invariably attends all complaints of 
the lower bowels. It accounts, too, for all 
the varieties in the turns of the colon, which 
we meet with in so great a degree in different 
animals. This property of the bile explains 
likewise the formation of fatty concretions in 
the gall-bladder so commonly met with, and 
which, from these experiments, appear to be 
produced by the action of the bile on the 
mucus secreted in the gall-bladder ; and it 
enables us to understand how want of the 
gall-bladder in children, from malformation, 
is attended with excessive leanness, notwith- 
standing a great appetite, and leads to an ear- 



ly death. Fat thus appears to be formed in 
the intestines, and from thence received into 
the circulation, and deposited in almost every 
part of the body. And as there appears to 
be no direct channels by which any super- 
abundance of it can be thrown out of the 
body, whenever its supply exceeds the con- 
sumption, its accumulation becomes a disease, 
and often a very distressing one. See BI- 
LIARY CONCRETIONS, MARGARINE, and IN- 
TESTINAL CONCRETIONS. 

ADIT, in mining, is a subterraneous pass- 
age slightly inclined, about six feet high, and 
two or three feet wide, begun at the bottom 
of a neighbouring valley, and continued up 
to the vein, for the purpose of carrying out 
the minerals and drawing off the water. If 
the mine require draining by a steam-engine 
from a greater depth, the water need be raised 
only to the level of the adit. There is a 
good account of the Cornish adits, by Mr 
W. Philips, Trans. Geol. Soc. vol. ii. ; and 
of adits in general, article Galerie, Brogni- 
art's Mineralogy, vol. ii. 

ADOPTER. A vessel with two necks 
placed between a retort and a receiver, and 
serving to increase the length of the neck of 
the former. See LABORATORY. 
ADULARIA. See FELSPAR. 
AERATED ALKALINE WATER. 
See ACID (CARBONIC). 

AERIAL ACID. See ACID (CARBO- 
NIC). 

AEROLITE, or METEORIC STONE. See 
METEORITE. 

AEROMETER. The name given by 
Dr M. Hall to an ingenious instrument of 
his invention, for making the necessary cor- 
rections in pneumatic experiments to ascer- 
tain the mean bulk of the gases. It consists 
of a bulb of glass 44 cubic inches capacity, 
blown at the end of a long tube whose capa- 
city is one cubic inch. This tube is inserted 
into another tube of nearly equal length, sup- 
ported on a sole. The first tube is sustained 
at any height within the second, by means of 
a spring. Five cubic inches of atmospheric 
air, at a medium pressure and temperature, 
are to be introduced into the bulb and tube, 
of the latter of which it will occupy one-half: 
the other half of this tube, and part of the 
tube into which it is inserted, are to be occu- 
pied by the fluid of the pneumatic trough, 
whether water or mercury. The point of the 
tube at which the air and fluid meet is to be 
marked by the figure 5, denoting 5 cubic 
inches. The upper and lower halves of the 
tube are each divided into five parts, repre- 
senting tenths of a cubic inch. The exter- 
nal tube has a scale of inches attached. 
Journal of Science, vol. v. See GAS, and 
APPENDIX. 

AEROSTATION. A name commonly, 
but not very correctly, given to the art of 
raising heavy bodies into the atmosphere, by 



AFFINITY. 



118 



AGARICUS. 



the buoyancy of heated air, or gases of small 
specific gravity, enclosed in a bag, which, 
from being usually of a spheroidal form, is 
called a balloon. Of all the possible shapes, 
the globular admits the greatest capacity 
under the least surface. Hence, of two bags 
of the same capacity, if one be spherical, and 
the other of any other shape, the former will 
contain the least quantity of cloth, or the least 
surface. The spheroidal form is therefore 
best fitted for aerostation. Varnished lute- 
string or muslin are employed for the en- 
velopes. The following table shows the re- 
lation betwixt the diameters, surfaces, and 
capacities of spheres : 

Diameters. Surfaces. Capacities. 

1 3.141 0.523 

2 12.567 4.188 

3 28.274 14.137 

4 50.265 33.51 

5 78.54 65,45 
10 314.159 523.6 
15 706.9 1767.1 
20 1256.6 4189. 
25 1963.5 8181. 
30 2827. 14137. 
40 5026. 33510. 

Having ascertained by experiment the 
weight of a square foot of the varnished 
cloth, we find, by inspection in the above 
table, a multiplier, whence we readily com- 
pute the total weight of the balloon. A 
cubic foot of atmospheric air weighs 527 gr. 
and a cubic foot of hydrogen about 40. But 
as the gas employed to fill balloons is never 
pure, we must estimate its weight at some- 
thing more. And perhaps, taking every thing 
into account, we shall find it a convenient 
and sufficiently precise rule for aerostation, 
to consider every cubic foot of included gas 
to have by itself a buoyancy of fully one 
ounce avoirdupois. Hence a balloon of 10 
feet diameter will have an ascerisional force 
of fully 524 oz. or 33 Ibs. minus the weight 
of the 314 superficial feet of cloth ; and one 
of 30 feet diameter, a buoyancy of fully 
14137 oz., or nearly 890 Ibs. minus the 
weight of the 2827 feet of cloth. On this 
calculation no allowance need be made for 
the seams of the balloon. See the article 
VARNISH. 

JETITES, or EAGLE STONE, is a name 
that has been given to a kind of hollow geodes 
of oxide of iron, often mixed with a larger or 
smaller quantity of silex and alumina, con- 
taining in their cavity some concretions which 
rattle on shaking the stone. It is of a dull 
pale colour, composed of concentric layers of 
various magnitudes, of an oval or polygonal 
form, and often polished. Eagles were said 
to carry them to their nests, whence their 
name; and superstition formerly ascribed 
wonderful virtues to them. 

AFFINITY (CHEMICAL). Sec AT- 
TRACTION (CHEMICAL). 



AGALMATOLITE. See BILDSTEIN. 

AGARICUS. The mushroom, a genus 
of the order Fungi. Mushrooms appear to 
approach nearer to the nature of animal mat- 
ter than any other productions of the vege- 
table kingdom, as, beside hydrogen, oxygen, 
and carbon, they contain a considerable por- 
tion of nitrogen, and yield ammonia by dis- 
tillation. Prof. Proust has likewise disco- 
vered in them the benzoic acid, and phosphate 
of lime. 

A few of the species are eaten in this 
country, but many are recorded to have pro- 
duced poisonous effects. Perhaps it is of 
importance, that they should be fresh, tho- 
roughly dressed, and not of a coriaceous 
texture. Our ketchup is made by sprinkling 
mushrooms with salt, and letting them stand 
till great part is resolved into a brown liquor, 
which is then boiled up with spices. 

In pharmacy two species of boletus have 
formerly been used under the name of aga- 
ric. The B. pini laricis, or male agaric of 
the shops, was given as a purgative, either in 
substance, or in an extract made with vine- 
gar, wine, or an alkaline solution : and the 
B. igniarius, spunk or touchwood, called fe- 
male agaric, was applied externally as a styp- 
tic, even after amputations. For this purpose 
the soft inner substance was taken and beat- 
en with a hammer, to render it still softer. 
That of the oak was preferred. 

The mushrooms, remarkable for the quick- 
ness of their growth and decay, as well as for 
the fetor attending their spontaneous decom- 
position, were unaccountably neglected by 
analytical chemists, though capable of re- 
warding their trouble ; as is evinced by the 
recent investigations and discoveries of MM. 
Vauquelin and Braconnot. The insoluble 
fungous portion of the mushroom, though it 
resembles woody fibre in some respects, yet 
being less soluble than it in alkalis, and yield- 
ing a nutritive food, is evidently a peculiar 
product, to which accordingly the name of 
fungin has been given. Two new vegetable 
acids, the boletic and fungic, were also fruits 
of these researches. 

1. Agaricus campestris, an ordinary ar- 
ticle of food, analyzed by Vauquelin, gave 
the following constituents : 1. Adipocere. 
On expressing the juice of the agaric, and 
subjecting the remainder to the action of 
boiling alcohol, a fatty matter is extracted, 
which falls down in white flakes as the al- 
cohol cools. It has a dirty white colour, a 
fatty feel like spermaceti, and, exposed to 
heat, soon melts, and then exhales the odour 
of grease. 2. An oily matter. 3. Vegetable 
albumen. 4. The sugar of mushrooms. 
5. An animal matter soluble in water and 
alcohol : on being heated it evolves the odour 
of roasting meat, like osmazome. 6. An ani- 
mal matter not soluble in alcohol. 7. Fun- 
gin. 8. Acetate of potash. 



AGARICUS. 



119 



AGATE. 



2. Agaricus volvaceus afforded Braconnot 
fungin, gelatin, vegetable albumen, much 
phosphate of potash, some acetate of potash, 
sugar of mushrooms, a brown oil, adipocere, 
wax, a very fugacious deleterious matter, un- 
combined acid, supposed to be the acetic, 
benzoic acid, muriate of potash, and a deal 
of water ; in all 14- ingredients. 

3. Agaricus acris or piperatus, was found 
by Braconnot, after a minute analysis, to 
contain nearly the same ingredients as the 
preceding, without the wax and benzoic acid, 
but with more adipocere. 

4. Agaricus stypticus. From twenty parts 
of this Braconnot obtained of resin and adi- 
pocere 1.8, fungin 16.7, of an unknown ge- 
latinous substance, a potash salt, and a fuga- 
cious acrid principle 1.5. 

5. Agaricus bulbosus was examined by 
Vauquelin, who found the following consti- 
tuents: An animal matter insoluble in al- 
cohol, osmazome, a soft fatty matter of a yel- 
low colour and acrid taste, an acid salt (not 
a phosphate). The insoluble substance of 
the agaric yielded an acid by distillation. In 
Orfila's Toxicology several instances are de- 
tailed of the fatal effects of this species of 
mushroom on the human body. Dogs were 
killed within 24 hours by small quantities of 
it in substance, and also by its watery and 
alcoholic infusions ; but water distilled from 
it was not injurious. It is curious that the 
animals experienced little inconvenience after 
swallowing it, during the first ten hours ; 
stupor, cholera, convulsions, and painful 
cramps, are the usual symptoms of the poison 
in men. The best remedy is an emetic. 

6. Agaricus theogolus. In this Vauquelin 
found sugar of mushrooms, osmazome, a bit- 
ter acrid fatty matter, an animal matter not 
soluble in alcohol, a salt containing a vegeta- 
ble acid. 

7. Agaricus muscarius. Vauquelin's ana- 
lysis of this species is as follows : The two 
animal matters of the last agaric, a fatty 
matter, sulphate, phosphate, and muriate of 
potash, a volatile acid from the insoluble 
matter. The following account from Orfila 
of the effects of this species on the animal 
economy is interesting. Several French sol- 
diers ate, at two leagues from Polosck in 
Russia, mushrooms of the above kind. Four 
of them, of a robust constitution, who con- 
ceived themselves proof against the conse- 
quences under which their feebler companions 
were beginning to suffer, refused obstinately 
to take an emetic. In the evening the fol- 
lowing symptoms appeared : Anxiety, sense 
of suffocation, ardent thirst, intense griping 
pains, a small and irregular pulse, universal 
cold sweats, changed expression of counte- 
nance, violet tint of the nose and lips, general 
trembling, fetid stools. The symptoms be- 
coming worse, they were carried to the hospi- 
tal. Coldness and livid colour of the limbs, 



a dreadful delirium, and acute pains, accom- 
panied them to the last moment. One of 
them sunk a few hours after his admission into 
the hospital ; the three others had the same 
fate in the course of the night. On opening 
their dead bodies, the stomach and intestines 
displayed large spots of inflammation and 
gangrene ; and putrefaction seemed advanc- 
ing very rapidly. 

AGARICUS MINERALIS, the moun- 
tain milk or mountain meal of the Germans, 
is one of the purest of the native carbonates 
of lime, found chiefly in the clefts of rocks, 
and at the bottom of some lakes, in a loose 
or semi-indurated form. It has been used 
internally in haemorrhages, strangury, gravel, 
and dysenteries ; and externally as an appli- 
cation to old ulcers, and weak and watery , 
eyes. 

M. Fabroni calls by the name of mineral 
agaric, or fossil meal, a stone of a loose con- 
sistence found in Tuscany in considerable 
abundance, of which bricks may be made, 
either with or without the addition of a twen- 
tieth part of argil, so light as to float in 
water ; and which he supposes the ancients 
used for making their floating bricks. This, 
however, is very different from the preceding, 
not being even of the calcareous genus, since 
it appears, on analysis, to consist of silex 55 
parts, magnesia 15, water 14, argil 12, lime 
3, iron 1. Kirwan calls it argillo-murite. 

AGATE. A mineral whose basis is cal- 
cedony, blended with variable proportions of 
jasper, amethyst, quartz, opal, heliotrope, and 
cornelian. Ribbon agate consists of alternate 
and parallel layers of calcedony with jasper, 
quartz, or amethyst. The most beautiful 
comes from Siberia and Saxony. It occurs 
in porphyry and gneiss. Brecciated agate ; 
a base of amethyst, containing fragments of 
ribbon agate, constitute this beautiful variety. 
It is of Saxon origin. Fortification agate is 
found in nodules of various imitative shapes, 
imbedded in amygdaloid. This occurs at 
Oberstein on the Rhine, and in Scotland. 
On cutting it across, and polishing it, the in- 
terior zig-zag parallel lines bear a considerable 
resemblance to the plan of a modern fortifi- 
cation. In the very centre, quartz and ame- 
thyst are seen in a splintery mass, surrounded 
by the jasper and calcedony. Mocha stone. 
Translucent calcedony, containing dark out- 
lines of arborization, like vegetable filaments, 
is called Mocha stone, from the place in 
Arabia where it is chiefly found. These cu- 
rious appearances were ascribed to deposits of 
iron or manganese, but more lately they have 
been thought to arise from mineralized plants 
of the cryptogamous class. Moss agate is a 
calcedony with variously coloured ramifica- 
tions of a vegetable form, occasionally tra- 
versed with irregular veins of red jasper. Dr 
M'Culloch has recently detected, what Dau- 
benton merely conjectured, in mocha and 



AGGREGATE. 



120 



AIR. 



moss agates, aquatic confervas, unaltered both 
in colour and form, and also coated with iron 
oxide. Mosses and lichens have also been 
observed, along with chlorite, in vegetations. 
An onyx agate set in a ring, belonging to the 
Earl of Powis, contains the chrysalis of a 
moth. Agate is found in most countries, 
chiefly in trap rocks and serpentine. Hollow 
nodules of agate, called geodes, present inte- 
riorly crystals of quartz, colourless or ame- 
thystine, having occasionally scattered crystals 
of stilbite, chabasie, and capillary mesotype. 
These geodes are very common. Bitumen 
has been found by M. Patrin in the inside of 
some of them, among the hills of Dauria, on 
the right bank of the Chilca. The small 
geodes of volcanic districts contain water oc- 
casionally in their cavities. These are chiefly 
found in insulated blocks of a lava having an 
earthy fracture. When they are cracked, the 
liquid escapes by evaporation : it is easily 
restored by plunging them for a little in hot 
water. Agates are artificially coloured by 
immersion in metallic solutions. Agates were 
more in demand formerly than at present. 
They were cut into cups, and plates for boxes ; 
and also into cutlass and sabre handles. They 
are still cut and polished on a considerable 
scale, and at a moderate price, at Oberstein. 
The surface to be polished is first coarsely 
ground by large millstones of a hard reddish 
sandstone, moved by water. The polish is 
afterwards given on a wheel of soft wood, 
moistened and imbued with a fine powder of 
a hard red tripoli found in the neighbourhood. 
M. Faujas thinks that this tripoli is produced 
by the decomposition of the porphyrated rock 
that serves as a gangue to the agates. The 
ancients employed agates for making cameos. 
( See CALCEDONY. ) Agate mortars are valu- 
ed by analytical chemists, for reducing hard 
minerals to an impalpable powder. For some 
interesting optical properties of agates, see 
LIGHT. 

The oriental agate is almost transparent, 
and of a vitreous appearance. The occidental 
is of various colours, and often veined with 
quartz or jasper. It is mostly found in small 
pieces covered with a crust, and often running 
in veins through rocks like flint and petro- 
silex, from which it does not seem to differ 
greatly. Agates are most prized when the 
internal figure nearly resembles some animal 
or plant. 

AGGREGATE. When bodies of the 
same kind are united, the only consequence 
is, that one larger body is produced. In this 
case, the united mass is called an aggregate, 
and does not differ in its chemical properties 
from the bodies from which it was originally 
made. Elementary writers call the smallest 
parts into which an aggregate can be divided 
without destroying its chemical properties, in- 
tegrant parts. Thus the integrant parts of 
common salt are the smallest parts which can 



be conceived to remain without change ; and 
beyond these, any further subdivision cannot 
be made without developing the component 
parts, namely, the alkali and the acid ; which 
are still further resolvable into their consti- 
tuent principles. 

AGRICULTURE, considered as a de- 
partment of chemistry, is a subject of vast 
importance, but hitherto much neglected. 
When we consider that every change in the 
arrangements of matter connected with the 
growth and nourishment of plants ; the com- 
parative values of their produce as food ; the 
composition and constitution of soils ; and the 
manner in which lands are enriched by ma- 
nure, or rendered fertile by the different pro- 
cesses of cultivation, we shall not hesitate to 
assign to chemical agriculture a high place 
among the studies of man. If land be un- 
productive, and a system of ameliorating it is 
to be attempted, the sure method of attaining 
this object is by determining the causes of its 
sterility, which must necessarily depend upon 
some defect in the constitution of the soil, 
which may be easily discovered by chemical 
analysis. Some lands of good apparent tex- 
ture are yet eminently barren ; and common 
observation and common practice afford no 
means of ascertaining the causes, or of re- 
moving the effect. The application of che- 
mical tests in such cases is obvious ; for the 
soil must contain some noxious principle, 
which may be easily discovered, and probably 
easily destroyed. Are any of the salts of 
iron present ? They may be decomposed by 
lime. Is there an excess of siliceous sand ? 
The system of improvement must depend on 
the application of clay and calcareous matter. 
Is there a defect of calcareous matter ? The 
remedy is obvious. Is an excess of vegetable 
matter indicated? It may be removed by 
liming, paring, and burning. Is there a defi- 
ciency of vegetable matter ? It is to be sup- 
plied by manure. Peat earth is a manure ; 
but there are some varieties of peats which 
contain so large a quantity of ferruginous 
matter as to be absolutely poisonous to plants. 
There has been no question on which more 
difference of opinion has existed, than that 
of the state in which manure ought to be 
ploughed into land ; whether recent, or when 
it has gone through the process of fermenta- 
tion. But whoever will refer to the simplest 
principles of chemistry, cannot entertain a 
doubt on the subject. As soon as dung be- 
gins to decompose, it throws off its volatile 
parts, which are the most valuable and most 
efficient. Dung which has fermented so as 
to become a mere soft cohesive mass, has 
generally lost from one-third to one-half of 
its most useful constituent elements. See the 
articles ANALYSIS, MANURE, SOILS, VEGE- 
TATION, and Sir H. Davy's Agricultural 
Chemistry. 

AIR was, till lately, used as the generic 



AIR. 



121 



AIR. 



name for such invisible and exceedingly rare 
fluids as possess a very high degree of elas- 
ticity, and are not condensable into the liquid 
state by any degree of cold hitherto produced ; 
but as this term is commonly employed to 
signify that compound of aeriform fluids 
which constitutes our atmosphere, it has been 
deemed advisable to restrict it to this signifi- 
cation, and to employ as the generic term 
the word GAS, (which see), for the different 
kinds of air, except what relates to our at- 
mospheric compound, 

AIR (ATMOSPHERICAL or COM- 
MON). The immense mass of permanently 
elastic fluid which surrounds the globe we 
inhabit, must consist of a general assemblage 
of every kind of air which can be formed by 
the various bodies that compose its surface. 
Most of these, however, are absorbed by wa- 
ter; a number of them are decomposed by 
combination with each other; and some of 
them are seldom disengaged in considerable 
quantities by the processes of nature. Hence 
it is that the lower atmosphere consists chiefly 
of oxygen and nitrogen, together with mois- 
ture and the occasional vapours or exhala- 
tions of bodies. 

That the air of the atmosphere is so trans- 
parent as to be invisible, except by the blue 
colour it reflects when in very large masses, 
as is seen in the sky or region above us, or 
in viewing extensive landscapes; that it is 
without smell, except that of electricity, which 
it sometimes very manifestly exhibits ; alto- 
gether without taste, and impalpable ; not 
condensable by any degree of cold into the 
dense fluid state, though easily changing its 
dimensions with its temperature ; that it gra- 
vitates and is highly elastic ; are among the 
numerous observations and discoveries which 
do honour to the sagacity of the philosophers 
of the seventeenth century. They likewise 
knew that this fluid is indispensably neces- 
sary to combustion ; but no one, except the 
great, though neglected John Mayow, ap- 
pears to have formed any proper notion of 
its manner of acting in that process. 

The air of the atmosphere, like other 
fluids, appears to be capable of holding bodies 
in solution. 

Mere heating or cooling does not affect the 
chemical properties of atmospherical air ; but 
actual combustion, or any process of the same 
nature, combines its oxygen, and leaves its 
nitrogen separate. Whenever a process of 
this kind is carried on in a vessel containing 
atmospherical air, which is enclosed either by 
inverting the vessel over mercury, or by stop- 
ping its aperture in a proper manner, it is 
found that the process ceases after a certain 
time; and that the remaining air (if a com- 
bustible body capable of solidifying the oxy- 
gen, such as phosphorus, have been employ- 
ed) has lost about a fifth part of its volume, 
and is of such a nature as to be incapable of 



maintaining any combustion for a second 
time, or of supporting the life of animals. 

The respiration of animals produces the 
same effect on atmospherical air as combus- 
tion does. When an animal is included in 
a limited quantity of atmospherical air, it dies 
as soon as the oxygen is consumed ; and no 
other air will maintain animal life but oxy- 
gen, or a mixture which contains it. Pure 
oxygen maintains the life of animals much 
longer than atmospherical air, bulk for bulk. 

It is to be particularly observed, however, 
that, in many cases of combustion, the oxy- 
gen of the air, in combining with the com- 
bustible body, produces a compound, not solid 
or liquid, but aeriform. The residual air will 
therefore be a mixture of the nitrogen of the 
atmosphere with the consumed oxygen, con- 
verted into another gas. Thus, in burning 
charcoal, the carbonic acid gas generated 
mixes with the residual nitrogen, and makes 
up exactly, when the effect of heat ceases, 
the bulk of the original air. The breathing 
of animals, in like manner, changes the oxy- 
gen into carbonic acid gas, without altering 
the atmospherical volume. 

There are many provisions in nature, by 
which the proportion of oxygen in the atmos- 
phere, which is continually consumed in re- 
spiration and combustion, is again restored 
to that fluid. In fact there appears, as far as 
an estimate can be formed of the great and 
general operations of nature, to be at least as 
great an emission of oxygen, as is sufficient 
to keep the general mass of the atmosphere 
at the same degree of purity. Most plants 
emit oxygen in the sunshine. Lastly, if to 
this we add the decomposition of water, there 
will be numerous occasions in which this 
fluid will supply us with disengaged oxygen ; 
while, by a very rational supposition, its hy- 
drogen may be considered as having entered 
into the bodies of plants, for the formation 
of oils, sugars, mucilages, &c. from which it 
may be again extricated. 

To determine the respirability or purity of 
air, it is evident that recourse must be had to 
its comparative efficacy in maintaining com- 
bustion, or some other equivalent process. 
This subject will be considered under the ar- 
ticle EUDIOMETER. 

From the latest and most accurate experi- 
ments, the proportion of oxygen in atmos- 
pheric air is by measure about 21 per cent; 
and it appears to be very nearly the same, 
whether it be in this country or on the coast 
of Guinea, on low plains or lofty mountains, 
or even at the height of 7250 yards above the 
level of the sea, as ascertained by Gay Lussac 
in his aerial voyage in September 1805. The 
remainder of the air is nitrogen, with a small 
portion of aqueous vapour, amounting to 
about 1 per cent in the driest weather, and a 
still less portion of carbonic acid, not exceed- 
ing a thousandth part of the whole. 



AIR. 



122 



ALABASTER. 



As oxygen and nitrogen differ in speci- 
fic gravity in the proportion of 1.1111 to 
0.9722, it has been presumed, that the oxy- 
gen would be more abundant in the lower 
regions, and the nitrogen in the higher, if 
they constituted a mere mechanical mixture j 
which appears contrary to the fact. On the 
other hand it lias been urged, that they can- 
not be in the state of chemical combination, 
because they both retain their distinct pro- 
perties unaltered, and no change of tempera- 
ture or density takes place on their union. 

To get rid of the difficulty, Mr Dalton of 
Manchester framed an ingenious hypothesis, 
that the particles of different gases neither 
attract nor repel each other ; so that one gas 
expands by the repulsion of its own particles, 
without any more interruption from the pre- 
sence of another gas, than if it were in a va- 
cuum. This would account for the state of 
atmospheric air, it is true; but it does not 
agree with certain facts. In the case of the 
carbonic acid gas in the Grotto del Cano, and 
over the surface of brewers' vats, why does 
not this gas expand itself freely upward, if 
the superincumbent gases do not press upon 
it? Mr Dalton himself, too, instances as an 
argument for his hypothesis, that oxygen and 
hydrogen gases, when mixed by agitation, do 
not separate on standing. But why should 
either oxygen or hydrogen require agitation 
to diffuse it through a vacuum, in which, ac- 
cording to Mr Dalton, it is placed ? 

The theory of Berthollet appears consis- 
tent with all the facts, and sufficient to ac- 
count for the phenomenon. If two bodies 
be capable of chemical combination, their 
particles must have a mutual attraction for 
each other. This attraction, however, may 
be so opposed by concomitant circumstances, 
that it may be diminished in any degree. 
Thus we know, that the affinity of aggrega- 
tion may occasion a body to combine slowly 
with a substance for which it has a powerful 
affinity, or even entirely prevent its combin- 
ing with it ; the presence of a third substance 
may equally prevent the combination ; and 
so may the absence of a certain quantity of 
caloric. But in all these cases the attraction 
of the particles must subsist, though dimi- 
nished or counteracted by opposing circum- 
stances. Now we know that oxygen and 
nitrogen are capable of combination ; their 
particles, therefore, must attract each other ; 
but in the circumstances in which they are 
placed in our atmosphere, that attraction is 
prevented from exerting itself to such a de- 
gree as to form them into a chemical com- 
pound, though it operates with sufficient force 
to prevent their separating by their difference 
of specific gravity. Thus the state of the 
atmosphere is accounted for, and every dif- 
ficulty obviated, without any new hypothe- 
sis. 

The exact specific gravity of atmospherical 



air, compared to that of water, is a very nice 
and important problem. By reducing to 60 
Fahr. and to 30 inclies of the barometer, the 
results obtained with great care by MM. Biot 
and Arago, the specific gravity of atmos- 
pherical air appears to be 0.001220, water 
being represented by 1.000000. This relation 
expressed fractionally is B 5 , or water is 820 
times denser than atmospherical air. Mr Rice, 
in the 77th and 78th numbers of the Annals 
of Philosophy, deduces from Sir George 
Shuckburgh's experiments 0.00120855 for 
the specific gravity of air. This number 
gives water to air as 827.437 to 1. If with 
Mr Rice we take the cubic inch of water = 
252.525 gr. then 100 cubic inches of air by 
Biot's experiments will weigh 30.808 grains, 
and by Mr Rice's estimate 30.51 9. He con- 
siders with Dr Prout the atmosphere to be a 
compound of 4 volumes of nitrogen and 1 of 
oxygen ; the specific gravity of the first being 
to that of the second as 1.11 11 to 0.9722. 
Hence 

0.8vol. nitr. sp. gr. 0.001166 == 0.000933 
0. 2 oxy. 0. 00 1 340 = 0. 000268 

0.001201 

^ The numbers are transposed in the Annals 
of Philosophy by some mistake. 

MM. Biot and Arago found the specific 
gravity of oxygen to be 1. 10359 

and that of nitrogen, 0.96913 

air being reckoned 1.00000 

Or compared to water as unity, 
Nitrogen is 0.001182338 
Oxygen, 0.001346379 

And 0.8 nitrogen = 0.00094587 

0.2 oxygen = 0.00026927 



And 0.79 nitrogen 
0.21 oxygen 



0.00121514 

= 0.000934 
= 0.000283 



0.001217 

A number which approaches very nearly to 
the result of experiment, Many analogies, 
it must be confessed, favour Dr Prout's pro- 
portions ; but the greater number of experi- 
ments on the composition and density of the 
atmosphere agree with Biot's results. No- 
thing can decide these fundamental chemical 
proportions, except a new, elaborate, and 
most minutely accurate series of experiments. 
We shall then know whether the atmosphere 
contains in volume 20 or 21 per cent of oxy- 
gen. See EQUIVALENTS, and GAS. 

ALALITE. See DIOPSIDE. 

ALABASTER. Among the stones which 
are known by the name of marble, and have 
been distinguished by a considerable variety 
of denominations by statuaries and others, 
whose attention is more directed to their ex- 
ternal character and appearance than their 
component parts, alabasters are those which 



ALBUMEN. 



123 



ALBUMEN. 



have a greater or less degree of imperfect 
transparency, a granular texture, are softer, 
take a duller polish than marble, and are 
usually of a whiter colour. Some stones, 
however, of a veined and coloured appear- 
ance, have been considered as alabaster, from 
their possessing the first-mentioned criterion ; 
and some transparent and yellow sparry stones 
have also received this appellation. 

M. Tissot hardens plaster casts and alabas- 
ter, by drying them hard in a baker's oven 
for twenty-four hours or longer, according 
to their thickness ; withdrawing and cooling 
them ; then dipping them twice in river wa- 
ter for a minute or two each time. The 
piece is then exposed to the air, and at the 
end of three or four days it acquires the 
hardness and density of marble, so as to bear 
polishing. 

ALBIN. A mineral discovered at Mo- 
naberg, near Aussig in Bohemia ; and being 
of an opaque white colour, has been called, 
by Werner, Albin. Aggregated crystalline 
laminae constitute massive albin. Small crys- 
tals of it in right prisms, whose summits con- 
sist of four quadrangular planes, are found 
sprinkled over mammelated masses in cavi- 
ties. See ZEOLITE. 

ALBITE. A mineral, in crystals fre- 
quently, or almost always, met under the 
form of hemitropes. These hemitropes are 
formed when two crystals are so joined to 
each other, that the upper plane of the one 
is applied upon the inferior plane of the 
other. See CLEAVELANDITE, which is the 
name given to this mineral. 

ALBUM GR^CUM. The white and 
solid excrement of dogs which subsist chiefly 
on bones, was received as a remedy in the 
medical art under the name of Album Grae- 
cum. It consists, for the most part, of the 
earth of bones or lime, in combination with 
phosphoric acid. 

ALBUMEN. This substance, which de- 
rives its name from the Latin for the white of 
an egg, in which it exists abundantly, and in 
its purest natural state, is one of the chief 
constituent principles of all the animal solids. 
Beside the white of egg, it abounds in the 
serum of blood, the vitreous and crystalline 
humours of the eye, and the fluid of dropsy. 
Fourcroy claims to himself the honour of 
having discovered it in the green fecula? of 
plants in general, particularly in those of the 
cruciform order, in very young ones, and in 
the fresh roots of trees, though Rouelle ap- 
pears to have detected it there long before. 
Vauquelin says it exists also in the mineral 
water of Plombieres. 

M. Seguin has found it in remarkable 
quantity in such vegetables as ferment with- 
out yeast, and afford a vinous liquor ; and 
from a series of experiments he infers, that 
albumen is the true principle of fermentation, 
and that its action is more powerful in pro- 



portion to its solubility, three different de- 
grees of which he found it to possess. 

The chief characteristic of albumen is its 
coagulability by the action of heat. If the 
white of an egg be exposed to a heat of about 
134 F. white fibres begin to appear in it, and 
at 160 it coagulates into a solid mass. In a 
heat not exceeding 2 12 it dries, shrinks, and 
assumes the appearance of horn. It is solu- 
ble in cold water before it has been coagu- 
lated, but not after; and when diluted with 
a very large portion, it does not coagulate 
easily. Pure alkalis dissolve it, even after 
coagulation. It is precipitated by muriate 
of mercury, nitro-muriate of tin, acetate of 
lead, nitrate of silver, muriate of gold, infu- 
sion of galls, and tannin. The acids and 
metallic oxides coagulate albumen. On the 
addition of concentrated sulphuric acid, it 
becomes black, and exhales a nauseous smell. 
Strong muriatic acid gives a violet tinge to 
the coagulum, and at length becomes satu- 
rated with ammonia. About 7 or 8 parts of 
acid to one part of albumen, cause a most 
intense blue colour, even at a low temper- 
ature; but its development is favoured by 
a temperature of about 80 F. Nitric acid, 
at 70 F., disengages from it abundance of 
azotic gas ; and if the heat be increased, 
prussic acid is formed, after which carbonic 
acid and carburetted hydrogen are evolved, 
and the residue consists of water containing a 
little oxalic acid, and covered with a lemon- 
coloured fat oil. If dry potash or soda be 
triturated with albumen, either liquid or solid, 
ammoniacal gas is evolved, and the calcina- 
tion of the residuum yields an alkaline prus- 
siate. 

On exposure to the atmosphere in a moist 
state, albumen passes at once to the state of 
putrefaction. 

Solid albumen may be obtained by agitat- 
ing white of egg with ten or twelve times its 
weight of alcohol. This seizes the water 
which held the albumen in solution; and 
this substance is precipitated under the form 
of white flocks or filaments, which cohesive 
attraction renders insoluble, and which con- 
sequently may be freely washed with water. 
Albumen thus obtained is like fibrin, solid, 
white, insipid, inodorous, denser than water, 
and without action on vegetable colours. It 
dissolves in potash and soda more easily 
than fibrin ; but in acetic acid and ammo- 
nia with more difficulty. When these two 
animal principles are separately dissolved in 
potash, muriatic acid added to the albumin- 
ous does not disturb the solution, but it pro- 
duces a cloud in the other. 

Fourcroy and several other chemists have 
ascribed the characteristic coagulation of al- 
bumen by heat to its oxygenation. But co- 
hesive attraction is the real cause of the phe- 
nomenon. In proportion as the temperature 
rises, the particles of water and albumen re- 



ALBUMEN. 



124 



ALCHEMY. 



cede from each other, their affinity diminishes, 
3hd then the albumen precipitates. However, 
by uniting albumen with a large quantity of 
water, we diminish its coagulating property to 
such a degree, that heat renders the solution 
merely opalescent. A new-laid egg yields a 
soft coagulum by boiling ; but when, by keep- 
ing, a portion of the water has transuded so as 
to leave a void space within the shell, the con- 
centrated albumen affords a firm coagulum. 
An analogous phenomenon is exhibited by 
acetate of alumina, a solution of which, being 
heated, gives a precipitate in flakes, which re- 
dissolve as the caloric which separated the par- 
ticles of acid and base escapes, or as the tem- 
perature falls. A solution containing I- 10th 
of dry albumen forms by heat a solid coagu- 
lum ; but when it contains only 1- 15th, it gives 
a glairy liquid. One thousandth part, how- 
ever, on applying heat, occasions opalescence. 
Putrid white of egg, and the pus of ulcers, 
have a similar smell. According to Dr Bos- 
tock, a drop of saturated solution of cor- 
rosive sublimate let fall into water containing 
Woo f albumen, occasions a milkiness and 
curdy precipitate. On adding a slight excess 
of the mercurial solution to the albuminous 
liquid, and applying heat, the precipitate 
which falls, being dried, contains in every 7 
parts 5 of albumen. Hence that salt is the 
most delicate test of this animal product. 
The yellow pitchy precipitate occasioned by 
tannin is brittle when dried, and not liable to 
putrefaction. But tannin, or infusion of 
galls, is a much nicer test of gelatin than of 
albumen. 

Phosphoric acid recently prepared, either 
by the action of nitric acid or phosphorus, 
or by combustion in air, caused an abundant 
precipitate in albumen. Recently ignited 
phosphoric acid has always this effect ; but 
after being kept in solution for a few days, it 
loses that property. 

The cohesive attraction of coagulated al- 
bumen makes it resist putrefaction. In this 
state it may be kept for weeks under water 
without suffering change. By long digestion 
in weak nitric acid, albumen seems converti- 
ble into gelatin. By the analysis of Gay Lus- 
sac and Thenard, 100 parts of albumen are 
formed of 52.883 carbon, 23.872 oxygen, 
7.540 hydrogen, 15.705 nitrogen ; or in 
other terms, of 52.883 carbon, 27.127 oxy- 
gen and hydrogen, in the proportions for con- 
stituting water, 15.705 nitrogen, and 4.285 
hydrogen in excess. The negative pole of a 
voltaic pile in high activity coagulates albu- 
men ; but if the pile be feeble, coagulation 
goes on only at the positive surface. Albu- 
men, in such a state of concentration as it 
exists in serum of blood, can dissolve some 
metallic oxides, particularly the protoxide of 
iron. Orfila has found white of egg to be 
the best antidote to the poisonous effects of 
corrosive sublimate on the human stomach, 



As albumen occasions precipitates with the 
solutions of almost every metallic salt, pro- 
bably it may act beneficially against other 
species of mineral poison. 

From its coagulability albumen is of great 
use in clarifying liquids. See CLARIFICA- 
TION. 

It is likewise remarkable for the property 
of rendering leather supple, for which purpose 
a solution of whites of eggs in water is used 
by leatheV-dressers ; and hence Dr Lobb, of 
Yeovil in Somersetshire, was induced to em- 
ploy this solution in cases of contraction and 
rigidity of the tendons, and derived from it 
apparent success. 

Vegetable albumen has an almost perfect 
resemblance to white of egg. It dissolves in 
alkalis, and when in excess the solutions are 
neutral. It then coagulates slightly by heat, 
but the principal part is retained in solution : 
it combines with acids, and when exactly 
saturated, the substance remains soluble, but 
excess of acid (except the acetic and phos- 
phoric) precipitates it. Prior to the action of 
potash, the vegetable albumen dissolves feebly 
in vinegar or phosphoric acid ; but by ebulli- 
tion with these acids, it forms a transparent 
colourless jelly of considerable volume. Sou- 
beiran has shewn, that the azotized principle 
contained in emulsive seeds, and particularly 
in almonds, has all the properties of white of 
egg ; it is in fact the same substance as ve- 
getable albumen. Vegetable albumen may 
be procured by the following process : 
Boil gluten with successive portions of alco- 
hol, until the latter ceases to become turbid 
by cooling : mix these solutions with water, 
and distil ; as the aqueous residuum cools, a 
glutinous coherent mass will separate, re- 
sembling gluten. It is vegetable gelatin, 
and the same substance as that separated by 
Einhof 's process from barley, &c. The sub- 
stance insoluble in alcohol is vegetable albu- 
men. 

ALBURNUM. The interior white bark 
of trees. 

ALCARRAZAS. A species of porous 
pottery made in Spain, for the purpose of 
cooling water by its transudation and copious 
evaporation from the sides of the vessel. M. 
Darcet gives the following as the analysis of 
the clay which is employed for the purpose : 
60 calcareous earth, mixed with alumina and 
a little peroxide of iron, and 36 of siliceous 
earth, mixed with a little alumina. In work- 
ing up the earths with water, a quantity of 
salt is added, and dried in it. The pieces are 
only half baked. 

ALCHEMY. A title of dignity given 
in the dark ages, by the adepts, to the mys- 
tical art by which they professed to find the 
philosopher's stone, that was to transmute 
base metals into gold, and prepare the elixir 
of life. Though avarice, fraud, and folly, 
were their motives, yet their experimental 



ALCdHOL. 



1-25 



ALCOHOL. 



researches were instrumental in promoting 
the progress of chemical discovery. Hence, 
in particular, metallic pharmacy derived its 
prigin. 

ALCOHOL. This term is applied to the 
pure spirit obtained by distillation from all 
liquids that have undergone vinous fermen- 
tation. 

It appears to be essential to the fermen- 
tation of alcohol, that the fermenting fluid 
should contain saccharine matter, which is 
indispensable to that species of fermentation 
called vinous. In France, where a great deal 
of wine is made, particularly at the com- 
mencement of the vintage, that is too weak 
to be a saleable commodity, it is a common 
practice to subject this wine to distillation, 
in order to draw off the spirit ; and as the 
essential oil that rises in this process is of a 
more pleasant flavour than that of malt or 
melasses, the French brandies are preferred 
to any other ; though even in the flavour of 
these there is a difference, according to the 
wine from which they are produced. In the 
West Indies a spirit is obtained from the juice 
of the sugar-cane, which is highly impreg- 
nated with its essential oil, and well known 
by the name of rum. The distillers in this 
country use grain, or melasses, whence they 
distinguish the products by the name of malt 
spirits and melasses spirits. 

As the process of malting develops the sac- 
charine principle of grain, it would appear to 
render it fitter for the purpose ; though it is 
the common practice to use about six parts 
of raw grain with one of malt. For this two 
reasons may be assigned : by using raw grain 
the expense of malting is saved, as well as 
the duty on malt ; and the process of malting 
requires some nicety of attention, since, if it 
be carried too far, part of the saccharine mat- 
ter is lost, and if it be stopped too soon, this 
matter will not be wholly developed. Besides, 
if the malt be dried too quickly, or by an un- 
equal heat, the spirit it yields will be less in 
quantity, and more unpleasant in flavour. 
Another object of economical consideration 
is, what grain will afford the most spirit in 
proportion to its price, as well as the best in 
quality. Barley appears to produce less spirit 
than wheat ; and if three parts of raw wheat 
be mixed with one of malted barley, the pro- 
duce is said to be particularly fine. This is 
the practice of the distillers in Holland for 
producing a spirit of the finest quality ; but 
in England they are expressly prohibited from 
using more than one part of wheat to two of 
other grain. Rye, however, affords still more 
spirit than wheat. 

The practice with the distillers in Scotland 
is, to use one part of malted with from four 
to nine parts of unmalted grain. This mix- 
ture yields an equal quantity of spirit, and at 
a much cheaper rate than when the forrper 
proportions are taken. 



Whatever be the grain employed, it must 
be coarsely ground, and then mixed carefully 
with a little cold water, to prevent its run- 
ning into lumps : water about 140 F. may 
then be added, till it is sufficiently mashed ; 
and to the drained-off wort yeast is added. 
The wort is allowed to ferment in a covered 
vessel, to which, however, the air can have 
access. Attention must be paid to the tem- 
perature : for if it exceed 87 F. the fermen- 
tation will be too rapid ; if it be below 60, 
the fermentation will cease. The mean be- 
tween these will generally be found most fa- 
vourable. In this country it is the more 
common practice to mash the grain as for 
brewing malt liquors, and boil the wort. But 
in whichever way it be prepared, or if the wash 
(so the liquor intended for distillation is call- 
ed) be made from melasses and water, due 
attention must be paid to the fermentation, 
that it be continued till the liquor grows fine, 
and pungent to the taste, which will generally 
be about the third day, but not so long as to 
permit the acetous fermentation to commence. 

In this state the wash is to be committed 
to the still, (of which, including the head, it 
should occupy at least three-fourths), and dis- 
tilled with a gentle heat as long as any spirit 
comes over, which will be till about half the 
wash is consumed. The more slowly the 
distillation is conducted, the less will the pro- 
duct be contaminated with essential oil, and 
the less danger will there be of empyreuma. 
A great saving of time and fuel, however, 
may be obtained by making the still very 
broad and shallow, and contriving a free exit 
for the steam. This was at one time carried 
to such a pitch in Scotland, that a still mea- 
suring 43 gallons, and containing 16 gallons 
of wash, has been charged and worked no less 
than four hundred and eighty times in the 
space of 24 hours. This would be incredi- 
ble, were it not established by unquestionable 
evidence. See LABORATORY, article STILL. 

The above wonderful rapidity of distillation 
has now ceased, since the excise duties have 
been levied on the quantity of spirit produc- 
ed, and not, as formerly, by the size of the 
still. Hence, too, the spirit is probably im- 
proved in flavour. 

The first product, technically termed low 
wine, is again to be subjected to distillation ; 
the latter portions of what comes over, called 
feints, being set apart to be put into the wash- 
still at some future operation. Thus a large 
portion of the watery part is left behind. 
The second product, termed raw spirit, being 
distilled again, is called rectified spirit. It is 
calculated, that a hundred gallons of malt or 
corn wash will not produce above twenty of 
spirit, containing 60 parts of alcohol to 50 of 
water: the same of cyder wash, 15 gallons; 
and of melasses wash, 22 gallons. The most 
spirituous wines of France, those of Langue- 
doc, Guienne, and Rousillon, yield, accord- 



ALCOHOL. 



126 



ALCOHOL. 



ing to Chaptal, from 20 to 25 gallons of ex- 
cellent brandy from 100; but those of Bur- 
gundy and Champagne much less. Brisk 
wines containing much carbonic acid, from 
the fermentation having been stopped at an 
early period, yield the least spirit. 

The spirit thus obtained ought to be co- 
lourless, and free from any disagreeable fla- 
vour ; and in this state it is fittest for phar- 
maceutical purposes, or the extraction of tinc- 
tures. But for ordinary sale something more 
is required. The brandy of France, which is 
most in esteem here, though perfectly colour- 
less when first made, and often preserved so 
for use in that country by being kept in glass 
or stone bottles, is put into new oak casks 
for exportation, whence it soon acquires an 
amber colour, a peculiar flavour, and some- 
thing like an unctuosity of consistence. As 
it is not only prized for these qualities, but 
they are commonly deemed essential to it, 
the English distiller imitates by design these 
accidental qualities. The most obvious and 
natural method of doing this, would be by 
impregnating a pure spirit with the extrac- 
tive, resinous, and colouring matter of oak 
shavings ; but other modes have been con- 
trived. The dulcified spirit of nitre, as it is 
called, is commonly used to give the flavour ; 
and catechu, or burnt sugar, to impart the 
desired colour. A French writer has recom- 
mended three ounces and a half of finely 
powdered charcoal, and four ounces and a 
half of ground rice, to be digested for a fort- 
night in a quart of malt spirit 

The finest gin is said to be made in Hol- 
land, from a spirit drawn from wheat mixed 
with a third or fourth part of malted barley, 
and twice rectified over juniper berries ; but 
in general rye meal is used instead of wheat. 
They pay so much regard to the wateY em- 
ployed, that many send vessels to fetch it on 
purpose from the Meuse ; but all use the 
softest and clearest river water they can get. 
In England it is the common practice to add 
oil of turpentine, in the proportion of two 
ounces to ten gallons of raw spirit, with three 
handfuls of bay salt, and drawn off till the 
feints begin to rise. 

But corn or melasses spirit is flavoured 
likewise by a variety of aromatics, with or 
without sugar, to please different palates : all 
of which are included under the general tech- 
nical term of compounds or cordials* 

Other articles have been employed, though 
not generally, for the fabrication of spirit, as 
carrots and potatoes ; and we are lately in- 
formed by Professor Proust, that from the 
fruit of the carob tree he has obtained good 
brandy, in the proportion of a pint from five 
pounds of the dried fruit. 

It is stated, that the juice of the berries of 
the sorbus aucuparia (mountain-ash), are 
now used in the north of France for the 
production of spirit ; and the result is said to 



be equal to the finest distillation from fer- 
mented grapes for brandy. Charcoal is used 
in the second distillation to improve the 
flavour. 

To obtain pure alcohol, different processes 
have been recommended. Boerhaave re- 
commended for this purpose muriate of soda, 
added hot to the spirit. But the subcarbo- 
nate of potash is preferable. About a third 
of the weight of the alcohol should be added 
to it in a glass vessel, well shaken, and then 
suffered to subside. The salt will be mois- 
tened by the water absorbed from the alco- 
hol ; which being decanted, more of the salt 
is to be added ; and this is to be continued till 
the salt falls dry to the bottom of the vessel. 
The alcohol in this state will be reddened by 
a portion of the pure potash, which it will 
hold in solution, from which it must be freed 
by distillation in a water bath. Dry muriate 
of lime may be substituted advantageously 
for the alkali. 

By enclosing dilute alcohol in a bladder, 
the water exudes, and the spirit is concen- 
trated. Soemmering says, that if we put 
alcohol of a moderate strength into an ox's 
bladder, or a calf's, coated with isinglass, and 
suspend it over a sand bath, in a few days 
the alcohol will lose one-fourth of its bulk, 
and be found quite free from water, or be- 
come absolute alcohol. Gior. di Fisica, vii. 
239. S 

J& alcohol is much lighter than water, its 
specific gravity is adopted as the test of its 
purity. Lowitz asserts that he has obtained 
it at 791, by adding as much alkali as nearly 
to absorb the spirit ; but the temperature is 
not indicated. In the shops it is about 835 
or 840 : according to the London College it 
should be 825. 

It is by no means an easy undertaking to 
determine the strength or relative value of 
spirits, even with sufficient accuracy for com- 
mercial purposes. 

The importance of this object also for the 
purposes of revenue, induced the British 
government to employ Sir Charles Blagden 
to institute a very minute accurate series of 
experiments. These may be considered as 
fundamental results ; for which reason, I 
shall give a summary of their tabular re- 
sults, from the Philosophical Transactions 
for 1790. 

The precise specific gravity of the pure 
spirit employed was .82514 ; but to avoid an 
inconvenient fraction, it is taken, in con- 
structing the table of specific gravities, as 
.825 only, a proportional deduction being 
made from all the other numbers. Thus the 
following table gives the true specific gravity, 
at the different degrees of heat, of a pure 
rectified spirit, the specific gravity of which 
at 60 is .825, together with the specific 
gravities of different mixtures of it with 
water at those different temperatures. 



ALCOHOL. 127 ALCOHOL. 

Real Specific Gravities at the different Temperatures. 



Heat. 


The 

pure 
spirit. 


100 
grains of 
pirit to 
5 gr. of 
water. 


100 
rains of 
pirit to 
Ogr. of 
water. 


100 
Drains of 
pirit to 
5 gr. of 
water. 


100 
grains of 
pirit to 
20 gr. of 
water. 


100 
grains of 
spirit to 
& gr. of 
water. 


100 
rains of 
pirit to 
jOgr. of 
water. 


100 
grains of 
pirit to 
35 gr. of 
water. 


100 
grains of 
spirit to 
40 gr. of 
water. 


100 
grains of 
spirit to 
45 gr. of 
water. 


100 
grains of 
spirit to 
50 gr. of 
water. 


30 


83896 


.84995 


85957 


86825 


.87585 


88282 


88921 


89511 


.90054 


.90558 


.91023 


35 


83672 


84769 


85729 


86587 


87357 


88059 


88701 


89294 


89839 


90345 


90811 


40 


83445 


84539 


85507 


86361 


87184 


87838 


88481 


89073 


89617 


90127 


90596 


45 


83214 


84310 


85277 


86131 


86905 


87613 


88255 


88849 


89396 


89909 


90380 


50 


82977 


84076 


85042 


85902 


86676 


87384 


88030 


88626 


89174 


89684 


90160 


55 


82736 


83834 


84802 


85664 


86441 


87150 


87796 


88393 


88945 


89458 


89933 


60 


82500 


83599 


84568 


85430 


86208 


86918 


87569 


88169 


88720 


89232 


89707 


65 


82262 


83362 


84334 


85193 


85976 


86686 


87337 


87938 


88490 


89006 


89479 


70 


82023 


83124 


84092 


84951 


85736 


86451 


87105 


87705 


88254 


88773 


89252 


75 


81780 


82878 


83851 


84710 


85496 


86212 


86864 


87466 


88018 


88538 


89018 


80 


81530 


82631 


83603 


84467 


85248 


85966 


86622 


87228 


87776 


88301 


88781 


85 


81291 


82396 


83371 


84243 


85036 


85757 


86411 


87021 


87590 


88120 


88609 


90 


81044 


82150 


83126 


84001 


84797 


85518 


86172 


86787 


87360 


87889 


88376 


95 


80794 


81900 


82877 


83753 


84550 


85272 


85928 


86542 


87114 


87654 


88146 


100 


80548 


81657 


82639 


83513 


84038 


85031 


85688 


86302 


86879 


87421 


87915 



Heat. 


100 
grains of 
pirit to 
55 gr. of 
water. 


100 
grains of 
pirit to 
60 gr. of 
water. 


100 
grains of 
pint to 
5 gr. of 
water. 


100 
grains of 
pirit to 
70 gr. of 
water. 


100 

Drains of 
pirit to 
75 gr. of 
water. 


100 
grains of 
pirit to 
80 gf . of 
water. 


100 
grains of 
spirit to 
85 gr. of 
water. 


100 
grains of 
spirit to 
90 gr. of 
water. 


100 
grains of 
spirit to 
95 gr. of 
water. 


100 
grains of 
spirit to 
lOOgr.of 
water. 


30 


91449 


91847 


92217 


92563 


92889 


93191 


.93474 


.93741 


93991 


.94222 


35 


91241 


91640 


92009 


92355 


92680 


92986 


93274 


93541 


93790 


94025 


40 


91026 


91428 


91799 


92151 


92476 


92783 


93072 


93341 


93592 


93827 


45 


90812 


91211 


91584 


91937 


92264 


92570 


92859 


93131 


93382 


93621 


50 


90596 


90997 


91370 


91723 


92051 


92358 


92647 


92919 


93177 


93419 


55 


90367 


90768 


91144 


91502 


91837 


92145 


92436 


92707 


92963 


93208 


60 


90144 


90549 


90927 


91287 


91622 


91933 


92225 


92499 


92758 


93002 


65 


89920 


90328 


90707 


91066 


91400 


91715 


92010 


92283 


92546 


92794 


70 


89695 


90104 


90484 


90847 


91181 


91493 


91793 


92069 


92333 


92580 


75 


89464 


89872 


90252 


90617 


90952 


91270 


91569 


91849 


92111 


92364 


80 


89225 


89639 


90021 


90385 


90723 


91046 


91340 


91622 


91891 


92142 


85 


89043 


89460 


89843 


90209 


90558 


90882 


91186 


91465 


91729 


91969 


90 


88817 


89230 


89617 


89988 


90342 


90668 


90967 


91248 


91511 


91751 


95 


88588 


89003 


89390 


89763 


90119 


90443 


90747 


91029 


91290 


91531 


100 


88357 


88769 


89158 


89536 


89889 


90215 


90522 


90805 


91066 


91310 





95 


90 


85 


80 


75 


70 


65 


60 


55 


50 




grains of 


grains of 


grains of 


grains of 


grains of 


grains of 


grains of grains of 


grains of 


grains of 


Heat. 


spirit to 
lOOgr.of 


spirit to 
lOOgr.of 


spirit to 
lOOgr.of 


spirit to 
lOOgr.of 


spirit to 
lOOgr.of 


pirit to 
lOOgr.of 


pirit to spirit to 
lOOgr.of lOOgr.of 


spirit to 
lOOgr.of 


spirit to! 
100 gr. of 




water. 


water. 


water. 


water. 


water. 


water. 


water. I water. 


water. 


water. 


30 


.94447 


.94675 


.94920 


.95173 


95429 


95681 


95944 '.96209 


.96470 


.96719 


35 


94249 


94484 


94734 


94988 


95246 


95502 


95772 


96048 


96315 


96579 


40 


94058 


94295 


94547 


94802 


95060 


95328 


95602 


95879 


96159 


96434 


45 


93860 


94096 


94348 


94605 


94871 


95143 


95423 


95705 


95993 


96280 


50 


93658 


93897 


94149 


94414 


94683 


94958 


95243 


95534 


95831 


96126 


55 


93452 


93696 


93948 


94213 


94486 


94767 


95057 


95357 


95662 


95966 


60 


93247 


93493 


93749 


94018 


94296 


94579 


94876 


95181 


95493 


95804 


65 


93040 


93285 


93546 


93822 


94099 


94388 


94689 


95000 


95318 


95635 


70 


92828 


93076 


93337 


93616 


93898 


94193 


94500 


94813 


95139 


95469 


75 


92613 


92865 


93132 


93413 


93695 


93989 


94301 


94623 


94957 


95292 


80 


92393 


92646 


92917 


93201 


93488 


93785 


94102 


94431 


94768 


95111 



ALCOHOL. 



128 



ALCOHOL. 





45 


40 


35 


30 


25 


20 


15 


10 


5 




grains of 


grains of 


grains of 


grains of 


grains of 


grains of 


grains of 


grains of 


grains of 


Heat. 


spirit to 


spirit to 


spirit to 


spirit to 


spirit to 


spirit to 


spirit to 


spirit to 


spirit to 




100 gr. of 


lOOgr.of 


lOOgr.of 


lOOgr.of 


lOOgr.of 


lOOgr.of 


leOgr.of 


lOOgr.of 


lOOgr.of 




water. 


water. 


water. 


water. 


water. 


water. 


water. 


water. 


water. 


30 


.96967 


.97200 


.97418 


.97635 


.97860 


.98108 


.98412 


98804 


.99334 


35 


96840 


97086 


97319 


97556 


-97801 


98076 


98397 


98804 


99344 


40 


96706 


96967 


97220 


97472 


97737 


98033 


98373 


98795 


99345 


45 


96563 


96840 


97110 


97384 


97666 


97980 


98338 


98774 


99338 


50 


96420 


96708 


96995 


97284 


97589 


97920 


98293 


98745 


99316 


55 


96272 


96575 


96877 


97181 


97500 


97847 


98239 


98702 


99284 


60 


96122 


96437 


96752 


97074 


97410 


97771 


98176 


98654 


99244 


65 


95962 


96288 


96620 


96959 


97309 


97688 


98106 


98594 


99194 


70 


95802 


96143 


96484 


96836 


97203 


97596 


98028 


98527 


99134 


75 


95638 


95987 


96344 


96708 


97086 


97495 


97943 


98454 


99066 


80 


95467 


95826 


96192 


96568 


96963 


97385 


97845 


98367 


98991 



From this table, when the specific gravity 
of any spirituous liquor is ascertained, it will 
be easy to find the quantity of rectified spirit 
of the above-mentioned standard contained 
in any given quantity of it, either by weight 
or measure. 

Dr Blagden concludes with observing, that 
as the experiments were made with pure 
spirit and water, if any extraneous substances 
are contained in the liquor to be tried, the spe- 
cific gravity in the tables will not give exactly 
the proportions of water and spirit in it. The 
substances likely to be found in spirituous li- 
quors, where no fraud is suspected, are essen- 
tial oils, sometimes empyreumatic, mucilagi- 
nous or extractive matter, and perhaps some 
saccharine matter. The effect of these, in 
the course of trade, seems to be hardly such 
as would be worth the cognizance of the Ex- 
cise, nor could it easily be reduced to certain 
rules. Essential and empyreumatic oils are 
nearly of the same specific gravity as spirit, 
in general rather lighter, and therefore, not- 
withstanding the mutual penetration, will 
probably make little change in the specific 
gravity of any spirituous liquor in which they 
are dissolved. The other substances are all 
heavier than spirit ; the specific gravity of 
common gum being 1.482, and of sugar 
1.606, according to the tables of M. Brisson. 
The effect of them, therefore, will be to make 
spirituous liquors appear less strong than they 
really are. 

The strength of spirits is determined, ac- 
cording to the existing laws, by Sikes's hy- 
drometer ; but as many dealers use Dicas's, 
I shall describe it here, and the former under 
DISTILLATION. 

It consists of a light copper ball, terminat- 
ing below with a ballast bottom, and above 
with a thin stem, divided into ten parts. The 
upper extremity of the stem is pointed, to re- 
ceive the little brass poises, or discs, having 
each a hole in its centre. These poises are 
numbered 0, 10, 20, 30, &c. up to 350, which 
is the lightest of the series, The intermediate 



units are given by the subdivisions on the 
stem. A graduated ivory scale, with a slid- 
ing rule and thermometer, accompanies the 
hydrometer, to make the correction for tem- 
perature. The first thing in using this in- 
strument, is to plunge the thermometer into 
a glass cylinder containing the spirits to be 
tried. The sliding rule has then the degree 
of temperature indicated, moved opposite to 
zero. The hydrometer is now placed in the 
liquid, and such a poise is put on as to sub- 
merge a portion of the stem. The weight, 
added to the number on the stem, gives a 
sum, opposite to which on the scale we find 
a quantity by which the particular spirit may 
exceed or fall short of proof. Thus, if it 
mark 20 under proof, it signifies that every 
100 gallons of that spirit would require to 
have 20 gallons of water abstracted from it 
to bring it up to proof. If it mark 10 over 
proof, we learn that every 100 gallons con- 
tain too little water by 10 gallons. When the 
thermometric degree of 60 is put opposite 
to zero, then the weights and value of the spi- 
rits have the following relations on the scale. 

102.5 denotes 20 under proof 

122.0 10 

143.5 Proof 

167. 10 over proof 

193. 20 

221. 30 

251. 40 

284.5 50 

322.5 60 

350.5 Alcohol. 

There is, besides, an upper line on the 
scale, which exhibits the relation of spirit to 
water reckoned unity. Thus, above 10 per 
cent over proof in the second line, we find 
in the upper line 8. From which we learn, 
that 8 of that spirit by bulk, will take 1 of 
water to bring it down to proof. At 60 
Fahr. I find that 10 over proof on Dicas 
corresponds to specific gravity 0.9085 

3* over proof to 0.9169 

Proof, - 0.9218 



ALCOHOL. 



129 



ALCOHOL. 



Now, by Gilpin's tables this indicates a 
compound of 100 grains of alcohol 0.825, 
and 85 grains of water. But by Lowitz's 
table in Crell's Annals the above specific 
gravity corresponds to 48 alcohol of 0.791 
at the temperature of 68, united to 52 of 
water, and cooled down to 60. Equal 
weights of that strong alcohol and water 



give, at 60, a specific gravity of 0.9175. 
By the Act of Parliament of 1762, the spe- 
cific gravity of proof was fixed at 0.916. It 
is at present to water as 12 to 13, or = 
0.923. See DISTILLATION. 

For the following table of the quantity of 
absolute alcohol, in spirits of different den- 
sities, we are indebted to Lowitz. 



100 j 
Ale. 


arts. 
Wat. 


Sp.gr 
At 68. 


avity. 
At 60. 


100 p 
Ale. 


arts. 
Wat. 


Sp.gi 

At 68. 


avity. 

At 60. 


100 p 
Ale. 


arts. 
Wat. 


Sp.gr 
At 68. 


avity. 
At 60. 


100 





0.791 


0.796 


66 


34 


0.877 


0.881 


32 


~68~ 


0.952 


0.955 


99 


1 


0.794 


0.798 


65 


35 


0.880 


0.883 


31 


69 


0.954 


0.957 


98 


2 


0.797 


0.801 


64 


36 


0.882 


0.886 


30 


70 


0.956 


0.958 


97 


3 


0.800 


0.804 


63 


37 


0.885 


0.889 


29 


71 


0.957 


0.960 


96 


4 


0.803 


0.807 


62 


38 


0.88T 


0.891 


28 


72 


0.959 


0.962 


95 


5 


0.805 


0.809 


61 


39 


0.889 


0.893 


27 


73 


0.961 


0.963 


94 


6 


0.808 


0.812 


60 


40 


0.892 


0.896 


26 


74 


0.963 


0.965 


93 


7 


0.811 


0.815 


59 


41 


0.894 


0.898 


25 


75 


0.965 


0.967 


92 


8 


0.813 


0.817 


58 


42 


0.896 


0.900 


24 


76 


0.966 


0.968 


91 


9 


0.816 


0.820 


57 


43 


0.899 


0.902 


23 


77 


0.968 


0.970 


90 


10 


0.818 


0.822 


56 


44 


0.901 


0.904 


22 


78 


0.970 


0.972 


89 


11 


0.821 


0.825 


55 


45 


0.903 


0.906 


21 


79 


0.971 


0.973 


88 


12 


0.823 


0.827 


54 


46 


0.905 


0.908 


20 


80 


0.973 


0.974 


87 


13 


0.826 


0.830 


53 


47 


0.907 


0.910 


19 


81 


0.974 


0.975 


86 


14 


0.828 


0.832 


52 


48 


0.909 


0.912 


18 


82 


0.976 


0.977 


85 


15 


0.831 


0.835 


51 


49 


0.912 


0.915 


17 


83 


0.977 


0.978 


84 


16 


0.834 


0.838 


50 


50 


0.914 


0.917 


16 


84 


0.978 


0.979 


83 


17 


0.836 


0.840 


49 


51 


0.917 


0.920 


15 


85 


0.980 


0.981 


82 


18 


0.839 


0.843 


48 


52 


0.919 


0.922 


14 


86 


0.981 


0.982 


81 


19 


0.842 


0.846 


47 


53 


0.921 


0.924 


13 


87 


0.983 


0.984 


80 


20 


0.844 


0.848 


46 


54 


0.923 


0.926 


12 


88 


0.985 


0.986 


79 


21 


0.847 


0.851 


45 


55 


0.925 


0.928 


11 


89 


0.986 


0.987 


78 


22 


0.849 


0.853 


44 


56 


0.927 


0.930 


10 


90 


0.987 


0.988 


77 


23 


0.851 


0.855 


43 


57 


0.930 


0.933 


9 


91 


0.988 


0.989 


76 


24 


0.853 


0.857 


42 


58 


0.932 


0.935 


8 


92 


0.989 


0.990 


75 


25 


0.856 


0.860 


41 


59 


0.934 


0.937 


7 


93 


0.991 


0.991 


74 


26 


0.859 


0.863 


40 


60 


0.936 


0.939 


6 


94 


0.992 


0.992 


73 


27 


0.861 


0.865 


39 


61 


0.938 


0.941 


5 


95 


0.994 




72 


28 


0.863 


0.867 


38 


62 


0.940 


0.943 


4 


96 


0.995 




71 


29 


0.866 


0.870 


37 


63 


0.942 


0.945 


3 


97 


0.997 




70 


30 


0.868 


0.872 


36 


64 


0.944 


0.947 


2 


98 


0.998 




69 


31 


0.870 


0.874 


35 


65 


0.946 


0.949 


1 


99 


0.999 




68 


32 


0.872 


0.878 


34 


66 


0.948 


0.951 





100 


1.000 




67 


33 


0.875 


0.879 


33 


67 


0.950 


0.953 











The most remarkable characteristic pro- 
perty of alcohol, is its solubility or combina- 
tion in all proportions with water ; a property 
possessed by no other combustible substance, 
except the acetic spirit obtained by distilling 
the dry acetates. When it is burnt in a 
chimney which communicates with the worm- 
pipe of a distilling apparatus, the product, 
which is condensed, is found to consist of 
water, which exceeds the spirit in weight 
about one-eighth part; or more accurately, 
100 parts of alcohol, by combustion, yield 
136 of water. If alcohol be burned in close 
vessels with vital air, the product is found to 
be water and carbonic acid. Whence it is 



inferred, that alcohol consists of hydrogen, 
united either to carbonic acid, or its acidifi- 
able base ; and that the oxygen uniting on 
the one part with the hydrogen, forms water ; 
and on the other with the base of the carbo- 
nic acid, forms that acid. 

Some ingenious experiments have been re- 
cently made on this subject by M. de Saussure. 
The alcohol he used had, at 62.8, a specific 
gravity of 0.8302; and by Richter's propor- 
tions it consisted of 13.8 water, and 86.2 of 
absolute alcohol. The vapour of alcohol was 
made to traverse a narrow porcelain tube ig- 
nited, from which the products passed along 
a glass tube about six feet in length, refrige- 
I 



ALCOHOL. 



130 



ALCOHOL. 



v rated by ice. A little charcoal was deposited 
in the porcelain, and a trace of oil in the 
glass tube. The resulting gas being analyzed 
in an exploding eudiometer, with oxygen, 
was found to resolve itself into carbonic acid 
and water. Three volumes of oxygen dis- 
appeared for every two volumes of carbonic 
acid produced; a proportion which obtains 
in the analysis by oxygenalion of olefiant 
gas. Now as nothing resulted but a com- 
bustible gas of this peculiar constitution, and 
condensed water equal to ^g? f tne origi- 
nal weight of the alcohol, we may conclude 
that vapour of water and olefiant gas are the 
sole constituents of alcohol. Subtracting 
the 13.8 per cent of water in the alcohol at 
the beginning of the experiment, the absolute 
alcohol of Richter will consist of 13.7 hydro- 
gen, 51 .98 carbon, and 34.32 oxygen. Hence 
M. Gay Lussac infers that alcohol, in va- 
pour, is composed of one volume olefiant gas, 
and one volume of the vapour of water, con- 
densed by chemical affinity into one volume. 
The sp. gr. of olefiant gas is 0.97804 
Of aqueous vapour is 0.62500 

Sum = 1.60304 

And alcoholic vapour is == 1.6133 
These numbers approach nearly to those 
which would result from two prime equiva- 
lents of olefiant gas combined with one of 
water ; or ultimately, three of hydrogen, two 
of carbon, and one of oxygen. 

The analytical experiments on alcohol were 
among the most satisfactory of any which I 
made on vegetable products, (see ANALYSIS 
VEGETABLE); for in repeated verifications 
the results agreed within one or at most two- 
hundredths of a grain. Alcohol, specific gra- 
vity 0.812, afforded me in 100 parts, 47.85 
carbon, 12.24 hydrogen, and 39.91 oxygen; 
or referring the last two to the composition of 
water, 44.9 of it, with 7.25 oxygen in excess. 
Such alcohol would therefore seem to consist 
of nearly 

Carbon, 3 atoms, 2.250 46.15 
Hydrogen, 6 0.625 12.82 

Oxygen, 2 2.000 40.03 

4.875 100.00 

Or of 3 atoms of olefiant gas = 2.625 
2 water = 2.250; 

And in volumes, 

3 vols. olefiant gas = 0.9722 X 3= 2.'9166, 

4 aqueous vapour = 0.625 X *== 2.5000. 
Thus alcohol 0.812, by the above analysis, 
which I believe merits confidence, differs from 
M. Gay Lussac's view of absolute alcohol de- 
duced from the experiments of M. de Satis- 
sure, in containing an additional volume of 
aqueous vapour. At the sp. gr. 0.814, alco- 
hol would have exactly this atomic constitu- 
tion. If the condensation be equal to the 
whole three volumes of olefiant gas, that is, 
if the seven volumes of constituent gases be- 



come four of alcohol vapour, we shall have the 
specific gravity at this strength = 1.3722 ; the 
additional volume of aqueous vapour produc- 
ing necessarily this abatement in the density. 
Messrs Dumas and Boullay have recently 
analyzed alcohol, and have given the follow- 
ing result: 

Carbon, 52.37 

Hydrogen, 13.31 

Oxygen, 34.61 

100.00 

This constitution will agree with my ex- 
periments, when allowance is made for the 
water present in alcohol at 0.812 over abso- 
lute alcohol. 

A considerable number of the uses of this 
fluid as a menstruum will pass under our ob- 
servation in the various articles of this work. 
The mutual action between alcohol and acids 
produces a light, volatile, and inflammable 
substance, called ether. (See ETHER.) Pure 
alkalis unite with spirit of wine, and form al- 
kaline tinctures. Few of the neutral salts 
unite with this fluid, except such as contain 
ammonia. The carbonated fixed alkalis are 
not soluble in it. From the strong attraction 
which exists between alcohol and water, it 
unites with this last in saline solutions, and 
in most cases precipitates the salt. This is a 
pleasing experiment, which never fails to sur- 
prise those who are unacquainted with che- 
mical effects. If, for example, a saturated 
solution of nitre in water be taken, and an 
equal quantity of strong spirit of wine be 
poured upon it, the mixture will constitute a 
weaker spirit, which is incapable of holding 
the nitre in solution ; it therefore falls to the 
bottom instantly, in the form of minute crys- 
tals. 

The degrees of solubility of many neutral 
salts in alcohol have been ascertained by ex- 
periments made by Macquer, of which an 
account is published in the Memoirs of the 
Turin Academy. The alcohol he employed 
was carefully freed from superabundant wa- 
ter by repeated rectifications, without addi- 
tion of any intermediate substance. The salts 
employed in his experiments were previously 
deprived of their water of crystallization by a 
careful drying. He poured into a matrass, 
upon each of the salts thus prepared, half an 
ounce of his alcohol, and set the matrass in a 
sand bath. When the spirit began to boil, 
he filtrated it while it was hot, and left it to 
cool, that he might observe the crystallizations 
which took place. He then evaporated the 
spirit, and weighed the saline residuums. He 
repeated these experiments a second time, with 
this difference, that instead of evaporating the 
spirit in which the salt had been digested, he 
set fire to it, in order to examine the pheno- 
mena which its flame might exhibit. The 
principal results of his experiments are sub- 
joined. 



ALCOHOL. 



131 



ALCOHOL. 



Quantity Salts soluble in 

of grains. 200 grains of spirit. 

4 Nitrate of potash, 

5 Muriate of potash, 
Sulphate of Soda, 

15 Nitrate of Soda, 

Muriate of Soda, 

Sulphate of ammonia, 

108 Nitrate of ammonia, 

24 Muriate of ammonia, 

288 Nitrate of lime, 

288 Muriate of lime, 

84- Nitrate of silver, 

204 Muriate of mercury, 

4 Nitrate of iron, 

36 Muriate of iron, 

48 Nitrate of copper, 

48 Muriate of copper, 



Peculiar phenomena of the flame. 

C Flame larger, higher, more ardent, yellow, 
\ and luminous. 

Large, ardent, yellow, and luminous. 

Considerably red. 

Yellow, luminous, detonating. 

Larger, more ardent, and reddish. 

None. 

Whiter, more luminous. 

None. 

f Larger, more luminous, red, and decrepi- 
\ tating. 

Like that of the calcareous nitre. 

None. 

Large, yellow, luminous, and decrepitating. 

Red and decrepitating. 

More white, luminous, and sparkling. 
C More white, luminous, and green ; much 
< smoke. The saline residuum became 
C black and burnt. 

Fine green, white, and red fulgurations. 



Macquer accompanies the relation of his 
experiments with many judicious reflections, 
not easily capable of abridgment. 

The alcohol he employed in the above ex- 
periments had a specific gravity of 0. 840. In 
analytical researches, alcohol affords frequent- 
ly a valuable agent for separating salts from 
each other. We shall therefore introduce the 
following additional table, derived chiefly 
from the experiments of Wenzel. 

100 parts of alcohol dissolve of 

Temp. 

Nitrate of Cobalt, at 54.5 100 parts 

Copper, 54.5 100 

Alumina, 54.5 100 

Lime, 125 

Magnesia, 180.5 290 

Muriate of Zinc, 54.5 100 

Alumina, 54.5 100 

Muriate of Magnesia, 180.5 547 

Iron, 180.5 100 

Copper, 180.5 100 

Acetate of Lead, 154.5 100 

At the boiling point, 100 parts of alcohol 
dissolve of muriate of lime 100 parts 

Nitrate of ammonia, - 89 

Corrosive sublimate, - 88.8 

Succinic acid, - - 74.0 

Acetate of soda, - - 46.5 
Nitrate of silver, - - 41.7 
Refined sugar, - - 24.6 

Boracic acid, - - 20.0 

Nitrate of soda, 9.6 

Acetate* of copper, - -'*. 7.5 
Muriate of ammonia, : - "**' 7. 1 

Superarseniate of potash, - 3.75 

Oxalate of potash, - - 2.92 

Nitrate of potash, - - 2.08 

Muriate of potash, - - 2.08 

Arseniate of soda, - - 1.58 

Arsenious acid, 1.25 

Tartrate of potash, - - 0.42 



It appears from the experiments of Kirwan, 
that dried muriate of magnesia dissolves more 
abundantly in strong than in weak alcohol. 
100 parts, of specific gravity 0.900, dissolve 
21.25; of 0.848, 23.75; of 0.834, 36.25; 
and of 0.817, 50 parts. The same holds to 
a more limited extent with acetate of lime ; 
2.4 grains being soluble in 100 of the first 
alcohol, and 4.88 in 100 of the last. The 
other salts which he dried dissolved more 
sparingly in the stronger than in the weaker 
alcohol. The temperature of the spirit was 
generally 60. 

All deliquescent salts are soluble in alco- 
hol. Alcohol holding the strontitic salts in 
solution, gives a flame of a rich purple ; the 
cupreous salts and boracic acid give a green ; 
the soluble calcareous, a reddish ; the barytic, 
a yellowish. For the effect of other salts on 
the colour of the flame, see a preceding table. 

The alcohol of 0.825 has been subjected to 
a cold of 91 without congealing. But 
Mr Hutton has given, in the Edinburgh En- 
cyclopaedia, article Cold, an account of his 
having succeeded in solidifying it by a cold 
of 1 10. The alcohol he employed had a 
density of 0.798 at 60. His process has 
been kept secret. See ACID (SULPHUROUS), 
for a mode of freezing alcohol by the evapo- 
ration of that acid in its liquefied state. The 
boiling point of alcohol of 0.825 is 176. 
Alcohol of 0.810 boils at 173.5. For the 
force of its vapour at different temperatures, 
and its specific heat, see CALORIC, and the 
Tables of Vapour at the end of the volume. 

When potassium and sodium are put in 
contact with the strongest alcohol, hydrogen 
is evolved. When chlorine is made to pass 
through alcohol in a Woolfe's apparatus, there 
is a mutual action. Water, an oily-looking 
substance, muriatic acid, a little carbonic acid, 
and carbonaceous matter, are the products. 



ALCOHOL. 



ALCOHOL. 



This oily substance does not redden turnsole, 
though its analyst |.y hc.it shews it to con- 
t.iiu muriatic acid. It is white, denser than 
water, has a cooling taste analogous to mint. 
nml a peculiar but not ethereous odour. It 
is very soluble in alcohol, but. scarcely in 
water. The strongest alkalis hardly operate 
on it 

It was at one time maintained, that alco- 
hol did not exist in wines, but was generated 
and evolved by the heat of distillation. On 
this subject M. Gay Lussac made some de- 
cisive experiments. He agitated wine with 
litharge in fine powder till the liquid became 
as limpid as water, and then saturated it with 
subcarbonate of potash. The alcohol imme- 
diately separated, and floated on the top. He 
distilled another portion of wine in nicuo t at 
50 Fahr. a temperature considerably below 
that of fermentation. Alcohol came over. 
Mr Hrandc proved the same position by sa- 
turating wine with subacetate of lead, and 
adding potash. 

MM. Ail.un and Duportal have substitut- 
- redistillations used in converting 
eer into alcohol, a single process of 
ance. l-'rom the capital ot* the still 
U-d into .1 lar;';c copper recipient. 
ined by a secoiul tube to a second 
and so on through a series of four 
rranged like a \\ oolfe's apparatus. 
essel communicates with the worm 



ed for tl 

wine or 1 

great clo, t 

a tube is 

This is j< 

recipient, 

vessels. ., 

The last 

of the first rcfri 

the still, and tin 

charged with th 

When ebullition 

vapour issuing fr 



eratory. This, the body of 
two recipients nearest it, are 
wine or fermented liquor. 

takes place in the still, the 
m it communicates soon 



the boiling temperature to the liquor in the 
two recipients. From these the volatilized 
alcohol will rise and pass into the third ves- 
sel, which is empty. After communicating 

a certain heat to it, a portion of the finer or 
less condensable spirit will pass into the 
fourth, and thence, in a little, into the worm 
of the first refrigeratory. The wine round 
the worm will likewise acquire heat, but more 
slowly. The vapour that in that event may 
p.iss uncondcnsed through the first worm, is 
conducted into a second, surrounded with 
cold water. Whenever the still is worked oil'. 
it is replenished by a stopcock from the near- 
est recipient, which, in its turn, is filled from 
the second, and the second from the first 
worm tub. It is evident, from this arrange- 
ment. that by keeping the ,'ul and 1th reci- 
pients at a certain temperature, we may cause 
alcohol, of any decree of lightness, t > form 
directly at the remote extremity of t!u appa- 
ratus. The utmost economy of fu ! and 
time is also secured, and a better tla on red 
spirit is obtained. The arrierc gout of bad 
spirit can scarcely be destroyed by infusion 
with charcoal and redistillation. In tins mode 
of operating, the taste and smell are excellent 
from the first. Several stills on the above 



principle have been constructed at Glasgow 
for the \Vcst India distillers, and have been 
found extremely advantageous. The Excise 
laws do not permit their employment in the 
home trade. 

A very ingenious still on the above princi- 
ples has been recently invented by Mr J. J. 
Saintmarc. It has the aspect of a copper 
tower, containing 9 or 10 stories, each apart- 
ment being divided from the one below by a 
horizontal partition or floor, pierced with 
openings or vertical pipes, admirably fitted 
for transferring to the highest stage a very 
fine concentrated spirit in an uninterrupted 
operation. The lowest floor alone is exposed 
to the naked fire, and the upper ones have 
their contents heated by the steam which it 
causes to ascend. The apparatus has an ap- 
pearance of complication, but I should think 
it quite simple and satisfactory in its per- 
formance. It has been made the subject of 
a patent. 

If sulphur in sublimation meet with the 
vapour of alcohol, a very small portion com- 
bines with it. which communicates a hydro- 
sulphurous smell to the fluid. The increased 
surface of the two substances appears to fa- 
vour the combination. It had been suppos- 
ed that this was the only way in which they 
could be united ; but M. Favre has lately 
asserted, that having digested two drams of 
flowers of sulphur in an ounce of alcohol, 
over a gentle fire, not sufficient to make it 
boil, for twelve hours, he obtained a solution 
that gave twenty-three grains of precipitate. 
A similar mixture left to stand for a month 
in a place exposed to the solar rays, afforded 
sixteen grains of precipitate ; and another, 
from which the light was excluded, gave 
thirteen grains. If alcohol be boiled with 
one-fourth of its weight of sulphur for an 
hour, and filtered hot, a small quantity of 
minute crystals will be deposited on cooling ; 
and the clear fluid will assume an opaline 
hue on being diluted with an equal quantity 
of water, in which state it will pass the filter, 
nor will any sediment be deposited for seve- 
ral hours. The alcohol used in the last men- 
tioned experiment did not exceed .840. 

Phosphorus is sparingly soluble in alcohol, 
but in greater quantity by heat than in cold. 
The addition of water to this solution affords 
an opaque milky fluid, which gradually be- 
comes clear by the subsidence of the phos- 
phorus. 

Earths seem to have scarcely any action 
upon alcohol. Quicklime, however, produces 
some alteration in this fluid, by changing its 
flavour, and rendering it of a yellow colour. 
A small portion is probably taken up. 

Soaps are dissolved with great facility in 
alcohol, with which they combine more rea- 
dily than with water. None of the metals, 
or their oxides, are acted upon by this fluid. 
Hesins, essential oils, camphor, bitumen, ami 



ALCOHOL. 



133 



ALIMENTARY. 



various other substances, are dissolved with 
great facility in alcohol, from which they 
may be precipitated by the addition of water. 
From its property of dissolving resins, it 
becomes the menstruum of one class of var- 
nishes. See VAKNISJI. 

Camphor is not only extremely soluble in 
alcohol, but assists the solution of resins in it. 
Fixed oils, when rendered drying by metallic 
oxides, arc soluble in it, as well as when 
combined with alkalis. 

Wax, spermaceti, biliary calculi, urea, and 
all the animal substances of a resinous nature, 
are soluble in alcohol; but it curdles milk, 
coagulates albumen, and hardens the muscu- 
lar fibre and coagulum of the blood. 

The uses of alcohol are various. As a sol- 
vent of resinous substances and essential oils, 
it is employed both in pharmacy and by the 
perfumer. When diluted with an equal quan- 
tity of water, constituting what is called proof 
spirit, it is used for extracting tinctures from 
vegetable and other substances, ; the alcohol 
dissolving the resinous parts, and the water 
the gummy. From giving a steady heat 
without smoke when burnt in a lamp, it was 
formerly much employed to keep water boil- 
ing on the tea-table. In thermometers, for 
measuring great degrees of cold, it is prefer- 
able to mercury. It is in common use for 
preserving many anatomical preparations, and 
certain subjects of natural history ; but to 
some it is injurious, the mollusca? for in- 
stance, the calcareous covering of which it in 
time corrodes. It is of considerable use too 
in chemical analysis, as appears under the 
different articles to which it is applicable. 

From the great expansive power of alco- 
hol, it has been made a question, whether it 
might not be applied with advantage in the 
working of steam-engines. From a series of 
experiments made by Betancourt it appears, 
that the steam of alcohol has, in all cases of 
equal temperature, more than double the 
force of that of water ; and that the steam of 
alcohol at 1 7<t Q F, is equal to that of water 
at 212. Thus there is a considerable dimi- 
nution of the consumption of fuel ; and where 
this is so expensive as to be an object of great 
importance, by contriving the machinery so 
as to prevent the alcohol from being lost, it 
may possibly at some future time be used 
with advantage, if some other fluid of great 
expansive power, and inferior price, be not 
found more economical. 

In my experiments on vapours I found, 
that the latent heat of that of alcohol is less 
than one-half that of water ; for which rea- 
son the former would serve well for impell- 
ing the pistons of steam-engines, were it not 
to act on the metals, which has been sur- 
mised. 

It was observed at the beginning of this 
article, that alcohol might be decomposed by 
transmission through a red-hot tube : it is also 



decomposable by the strong acids, and thus 
allords that remarkable product, KTHKH, and 

Ol.KlIM VlNI. 

ALK. Sec: I'.Ki it. 

ALUMHIC, or STILL. This part of 
chemical apparatus, used for distilling or se- 
parating volatile products, by first raising 
them by heat, and then condensing them into 
the liquid state by cold, is of extensive use in 
a variety of operations. It is described un- 
der the article LABORATORY. 

ALEMI3ROTH SALT. Corrosive mu- 
riate of mercury is rendered much more solu- 
ble in water, by the addition of muriate of 
ammonia. From this solution crystals are 
separated by cooling, which were called sal- 
. alembroth by the earlier chemists, and appear 
to consist of ammonia, muriatic acid, and 
mercury. 

ALGAROTH (POWDER OK). Among 
the numerous preparations which the alche- 
mical researches into the nature of antimony 
have afforded, the powder of algaroth is one. 
When butter of antimony is thrown into 
water, the greater part of the metallic oxide 
falls down in the form of a white powder, 
which is the powder of algaroth. It is vio- 
lently purgative and emetic in small doses of 
three or four grains. See ANTIMONY. 

ALIMENTARY SUBSTANCES, Hie 
chemical relations of these substances have 
lately formed the subject of an elaborate me- 
moir by Dr Prout. His first object was, to 
devise, if possible, an unexceptionable mode 
of determining the proportions of the three 
or four principles which, with few excep- 
tions, form organic bodies ; and after nume- 
rous trials, he adopted a method, founded 
upon the following well known principles 
When an organic product, containing three 
elements, hydrogen, carbon, and oxygen, is 
burnt in oxygen gas, one of three things 
must happen : 1. Tin- original bulk of oxy- 
gen gas may remain the same; in which case 
the hydrogen and oxygen in the substance 
must exist in it in the same proportions in 
which they exist in water ; or, 2. The origi- 
nal bulk of the oxygen may be increased ; in 
which case the oxygen must exist in the sub- 
stance in a greater proportion than it exists 
in water ; or, 3. The original bulk of the 
oxygen gas may be diminished ; in which 
case the hydrogen must predominate. Hence 
it is obvious, that in the first of these cases 
the composition of a substance may be de- 
termined, by simply ascertaining the quantity 
of carbonic acid gas yielded by a known 
quantity of it; while, in the other two, the 
same can be readily ascertained by means of 
the same data, and by noting the excess or 
diminution of the original bulk of the oxy- 
gen gas employed. 

Dr Prout's apparatus consists of two in- 
verted glass syphons, which act the part of 
gasometers : these are connected, when re- 



ALIMENTARY. 



134 



ALKALESCENT. 



quired, by a small green glass tube, in which 
the substance is to be decomposed and burnt. 
The syphons are veFy carefully graduated, so 
that the quantity of gas in them can be accu- 
rately estimated ; and are supplied with cocks 
both above and below, so that they can be 
filled with mercury, the mercury drawn off 
and gas introduced, the gas transferred 
through the green glass tube, or the contents 
retained in an undisturbed state, with the 
utmost readiness and ease. The substance 
to be decomposed may be put into a platina 
tray, and introduced alone into the green 
glass tube, and being there heated by a spirit 
lamp, be burnt in the gas passing over it ; or 
it may be mixed with pure siliceous sand ; 
or, what is most generally preferable, be , 
mixed with peroxide of copper, which is al- 
ways left, in consequence of the excess of 
oxygen gas used, in the state in which it was 
introduced. After the experiment, the volume 
of gas is easily corrected for pressure, and, if 
necessary, for temperature, and the carbonic 
acid ascertained by the removal and analysis 
of a portion. No correction is required for 
moisture, the gas always being used saturated 
with water. 

Dr Prout considers the principal alimentary 
substances as reducible to three great classes, 
the saccharine, the oily, and the albuminous; 
and his paper relates to the first of these. 
This, with certain exceptions, includes the 
substances in which, according to MM. Gay 
Lussac and Thenard, the oxygen and hydro- 
gen are in the same proportion as in water. 
Such substances are principally derived from 
the vegetable kingdom; and being at the 
same time alimentary, Dr Prout uses the 
terms saccharine principle and vegetable ali- 
ment as synonymous. 

The following tables shew some of Dr 
Prout's results with several substances, ex- 
treme care having been taken in every case 
to obtain the bodies pure, and new processes 
were often resorted to for that purpose. 

SUGAR. 
Carbon. Water. 

Pure sugar candy, 42. 85 57.15 

Impure sugar can- 
dy, - 41.5 to 42.5 58.5 to 57.5 

East India sugar 

candy, - 41.9 58.1 

English refined 

sugar, 41.5 to 42.5 58.5 to 57.5 

Maple sugar, 42.1 57.9 

Beet-root sugar, 42.1 57.9 

East India moist 

sugar, - 40.88 59.12 

Sugar of diabetic 
urine, - 36 to 40? 64 to 60? 

Sugar of Nar- 
bonne honey, 36.36 63.63 

Sugar from starch, 36 . 2 63. 8 



AMYLACEOUS PRINCIPLES. 

Carb. Wat. 
Fine wheat starch, - 37.5 62.5 

dried, (') 42.8 57.2 

highly dried, ( 2 ) 44.0 56.0 

Arrowroot, - 36.4 63.6 

dried,(3) . 42.8 57.8 

highly dried,(4) 44.4 55.6 
(0 Was dried between 200 and 212 for 
twenty hours, lost 12.5 per cent. 

( 2 ) Part of the former dried between 300 
and 350, for six hours, lost 2.3 per cent. 

(3) Dried as ('), lost 15 per cent 

(*) Part of the last, heated to 212 for six 
hours longer, lost 3.2 per cent more. 

LIGNIN or WOODY FIBRE. 

Obtained by rasping wood, and then pul- 
verizing it in a mortar; boiling the impal- 
pable powder in water till nothing more was 
removed ; then in alcohol ; again in water, 
and dried in the air till they ceased to lose 
weight. 

Carb. Wat. 
From box, - - 42.7 57.3 

dried,(0 - 50 50 

From willow, - 42.6 57.4 
dried,(') - 49.8 50.2 

(*) Dried at 212 for six hours, afterwards 
between 300 and 350 for six hours. That 
from box lost 14.6, that from willow 14.4 
per cent. 

Carb. 

Acetic acid, - 47.05 

Sugar of milk, - 40.00 

Manna sugar, - 38.7 

Gum arabic, - 36.3 



dried,(') 41.4 



Wat. 

52.95 

60 

61.3 

63.7 

58.6 



(') Dried between 200 and 212 for 20 
hours, lost 12.4 per cent. The same gum 
further heated to between 300 and 350 for 
six hours, lost only 2.6 per cent, and had be- 
come deep brown. 

Vegetable acids. Carbon. Water. Oxygen. 

Oxalic acid, 19.04 42.85 38.11 

Citric acid, 34.28 42.85 22.87 

Tartaric acid, 32.00 36.00 32.00 

Malic acid, 40.68 45.76 13.56 

Saclactic acid, 33.33 44.44 22.22 

ALIZARINE. See MADDER. 

ALKAHEST. The pretended universal 
solvent or menstruum of the ancient chemists. 
Kunckel has very well shewn the absurdity 
of searching for a universal solvent, by ask- 
ing, " If it dissolve all substances, in what 
vessels can it be contained ?" 

ALKALESCENT. Any substance in 
which alkaline properties are beginning to be 
developed, or to predominate, is termed alka- 
lescent. The only alkali usually observed to 
be produced by spontaneous decomposition is 
ammonia ; and from their tendency to pro- 
duce this, some species of vegetables, partj- 
cularly the cruciform, are styled alkalescent, 



ALKALI. 



135 



ALKALI. 



as are some animal substances. See P'ER- 

MENTATION (PUTRID). 

ALKALI. A term derived from kali, 
the Arabic name of a plant, from the ashes 
of which one species of alkaline substance 
can be extracted. Alkalis may be defined, 
those bodies which combine with acids, so as 
to neutralize or impair their activity, and pro- 
duce salts. Acidity and alkalinity are there- 
fore two correlative terms of one species of 
combination. When Lavoisier introduced 
oxygen as the acidifying principle, Morveau 
proposed hydrogen as the alkali fying princi- 
ple, from its being a constituent of volatile 
alkali or ammonia. But the splendid dis- 
covery by Sir H. Davy of the metallic bases 
of potash and soda, and of their conversion 
into alkalis by combination with oxygen, has 
banished for ever that hypothetical conceit. 
It is the mode in which the constituents are 
combined, rather than the nature of the con- 
stituents themselves, which gives rise to the 
acid or alkaline condition. Some metals, 
combined with oxygen, in one proportion pro- 
duce a body possessed of alkaline properties, 
in another proportion of acid properties. And 
on the other hand, ammonia and prussic acid 
prove that both the alkaline and acid condi- 
tions can exist independent of oxygen. These 
observations, by generalizing our notions of 
acids and alkalis, have rendered the defini- 
tions of them very imperfect. The difficulty 
of tracing a limit between the acids and al- 
kalis is still increased, when we find a body 
sometimes performing the functions of an 
acid, sometimes of an alkali. Nor can we 
diminish this difficulty by having recourse to 
the beautiful law discovered by Sir H. Davy, 
that oxygen and acids go to the positive pole, 
and hydrogen, alkalis, and inflammable bases, 
to the negative pole. We cannot in fact give 
the name of acid to all the bodies which go 
to the first of these poles, and that of alkali to 
those that go to the second ; and if we wish 
to define the alkalis, by bringing into view 
their electric energy, it would be necessary 
to compare them with the electric energy 
which is opposite to them. Thus we are al- 
ways reduced to define alkalinity by the pro- 
perty which it has of saturating acidity, be- 
cause alkalinity and acidity are two correla- 
tive and inseparable terms. M. Gay Lussac 
conceives the alkalinity which the metallic ox- 
ides enjoy, to be the result of two opposite pro- 
perties, the alkalifying property of the metal, 
and the acidifying of oxygen, modified both 
by the combination and by the proportions. 
The alkalis may be arranged into three 
classes: 1st, Those which consist of a me- 
tallic basis combined with oxygen. These 
are three in number, potash, soda, and lithia. 
2d, That which contains no oxygen, viz. am- 
monia. 3d, Those containing oxygen, hy- 
drogen, and carbon. In this class we have 
aconita, brucia, datum, delphia, byosciama, 



morphia, strychnia, quinia, cinchonina, and 
perhaps some other truly vegetable alkalis. 
These are called by the German chemists al- 
Raloids. (See VEGETABLE KINGDOM.) The 
order of vegetable ajkalis may be as nume- 
rous as that of vegetable acids. The earths, 
lime, baryta, and strontia, were enrolled 
among the alkalis by Fourcroy; but they 
have been kept apart by other systematic 
writers, and are called alkaline earths. 

Besides neutralizing acidity, and thereby 
giving birth to salts, the first four alkalis have 
the following properties: 

1st, They change the purple colour of many 
vegetables to a green, the reds to a purple, 
and the yellows to a brown. If the purple 
have been reddened by acid, alkalis restore 
the purple. 

2d, They possess this power on vegetable 
colours after being saturated with carbonic 
acid, by which criterion they are distinguish- 
able from the alkaline earths. 

3d, They have an acrid and urinous taste. 

4tf/i, They are powerful solvents or corro- 
sives of animal matter ; with which, as well 
as with fat of oils in general, they combine, 
so as to produce neutrality. 

5th, They are decomposed, or volatilized, 
at a strong red heat. 

6th, They combine with water in every 
proportion, and also largely with alcohol. 

7th, They continue to be soluble in water 
when neutralized with carbonic acid ; while 
the alkaline earths thus become insoluble. 

It is needless to detail at length Dr Mur- 
ray's speculations on alkalinity. They seem 
to flow from a partial view of chemical phe- 
nomena. According to him, either oxygen 
or hydrogen may generate alkalinity, but the 
combination of both principles is necessary to 
give this condition its utmost energy. " Thus 
the class of alkalis will exhibit the same rela- 
tion? as the class of acids. Some are corn- 
pounds of a base with oxygen ; such are the 
greater number of the metallic oxides, and 
probably of the earths. Ammonia is a com- 
pound of a base with hydrogen. Potash, 
soda, baryta, strontia, and probably lime, are 
compounds of bases with oxygen and hydro- 
gen ; and these last, like the analogous order 
among the acids, possess the highest power." 
Now, surely, perfectly dry and caustic baryta, 
lime, and strontia, as well as the dry potash 
and soda obtained by Gay Lussac and The- 
nard, are not inferior in alkaline power to the 
same bodies after they are slacked or com- 
bined with water. 100 parts of lime desti- 
tute of hydrogen, that is, pure oxide of cal- 
cium, neutralize 78 parts of carbonic acid. 
But 132 parts of Dr Murray's strongest lime, 
that is the hydrate, are required to produce 
the same alkaline effect. If we ignite nitrate 
of baryta, we obtain, as is well known, a per- 
fectly dry baryta, or protoxide of barium; 
but if we ignite crystallized baryta, we obtain 



ALKANET. 



136 



ALLOPHANE. 



the same alkaline earth combined with a prime 
equivalent of water. These two different 
states of baryta were demonstrated by M. 
Berthollet, in an excellent paper published 
in the 2d volume of the Memoires d'Arcueil, 
so far back as 1809. " The first baryta," 
(that from crystallized baryta), says he, " pre- 
sents all the characters of a combination : it 
is engaged with a substance which diminishes 
its action on other bodies, which renders it 
more fusible, and which gives it by fusion the 
appearance of glass. This substance is no- 
thing else than water ; but in fact, by adding 
a little water to the second baryta (that from 
ignited nitrate), and by urging it at the fire, 
we give it the properties of the first." Page 
47. 100 parts of baryta void of hydrogen, 
or dry baryta, neutralize 28t? of dry carbonic 
acid. Whereas 11 If parts" of the hydrate, 
or what Dr Murray has styled the most ener- 
getic, are required to produce the same effect. 
In fact, it is not hydrogen which combines 
with the pure barytic earth, but hydrogen 
and oxygen in a state of water. The proof 
of this is, that when carbonic acid and that 
hydrate unite, the exact quantity of water is 
disengaged. The protoxide of barium, or 
pure baryta, has never been combined with 
hydrogen by any chemist. 

ALKALI (MINERAL or FOSSIL). 
An old name of SODA. 

ALKALI (PHLOGISTICATED, or 
PRUSSIAN). When a fixed alkali is ig- 
nited with bullock's blood, or other animal 
substances, and lixiviated, it is found to be 
in a great measure saturated with the prussic 
acid : From the theories formerly adopted re- 
specting this combination, it was distinguish- 
ed by the name of phlogisticated alkali. See 
ACID (PRUSSIC). 

ALKALI (VOLATILE). See AM- 
MONIA. 

ALK ALIMETE R. The name first given 
by M. Descroizilles to an instrument or mea- 
sure of his graduation, for determining the 
quantity of alkali in commercial potash and 
soda, by the quantity of dilute sulphuric acid 
of a known strength which a certain weight 
of them could neutralize. 

ALKANET. The alkanet plant is a 
kind of bugloss, which is a native of the 
warmer parts of Europe, and cultivated in 
some of our gardens. The greatest quanti- 
ties are raised in Germany and France, par- 
ticularly about Montpellier, whence we are 
chiefly supplied with the roots. These are 
of a superior quality to such as are raised in 
England. This root imparts an elegant deep 
red colour to pure alcohol, to oils, to wax, 
and to all unctuous substances. The aqueous 
tincture is of a dull brownish colour ; as is 
likewise the spirituous tincture when inspis- 
sated to the consistence of an extract. The 
principal use of alkanet root is, that of colour- 
ing oils, unguents, and Hp-salves. Wax 



tinged with it, and applied on warm marble, 
stains it of a flesh colour, which sinks deep 
into the stone ; as the spirituous tincture 
gives it a deep red stain. 

As the colour of this root is confined to 
the bark, and the small roots have more bark 
in proportion to their bulk than the great 
ones, these also afford most colour. 

ALLAGITE. A carbo-silicate of man- 
ganese. 

ALLANITE. A mineral first recognized 
as a distinct species by Mr Allan, of Edin- 
burgh, to whose accurate knowledge and 
splendid collection the science of minera- 
logy has been so much indebted in Scotland. 
Its analysis and description, by Dr Thom- 
son, were published in the 6th volume of the 
Edinburgh Phil. Trans. M. Giesecke found 
it in a granite rock in West Greenland. It 
is massive, and of a brownish-black colour. 
External lustre, dull ; internal, shining and 
resinous ; fracture small conchoidal opaque 
greenish-grey streak scratches glass and 
hornblende brittle ; spec. grav. 3.5 to 4.0; 
froths and melts imperfectly before the blow- 
pipe into a black scoria. It consists, in 100 
parts, of silica 35.4, oxide of cerium 33.9, 
oxide of iron 25.4, lime 9.2, alumina 4.1, 
and moisture 4.0. It has been also found 
crystallized in four, six, or eight-sided prisms. 
It closely resembles gadolinite, but may be 
distinguished from the thin fragments of the 
latter, being translucent on the edges, and of 
a fine green colour, whereas those of the for- 
mer are commonly opaque and of a yellowish- 
brown. The ores of cerium, analyzed by Ber- 
zelius under the name of cerin, approach very 
closely in their composition to allanite. 

ALLOCHROITE. A massive opaque 
mineral, of a greyish, yellowish, or reddish 
colour. Quartz scratches it, but it strikes fire 
with steel. It has externally a glistening, 
and internally a glimmering lustre. Its 
fracture is uneven, and its fragments are 
translucent on the edges : sp. gr. 3.5 to 3.6. 
It melts before the blowpipe into a black 
opaque enamel. Vauquelin's analysis is the 
following: silica 35, lime 30.5, oxide of iron 
17, alumina 8, carbonate of lime 6, oxide of 
maganese 3.5. M. Brogniart says it is ab- 
solutely infusible without addition, and that 
it requires a flux, as phosphate of soda or am- 
monia. With these it passes through a beau- 
tiful gradation of colours. It is covered at 
first with a species of enamel, which becomes 
on cooling reddish-yellow, then greenish, and 
lastly of a dirty yellowish-white. He repre* 
sents it as pretty difficult to break. It was 
found by M. Dandrada in the iron mine of 
Virums, near Drammen in Norway. It is 
accompanied by carbonate of lime, protoxide 
of iron, and sometimes brown garnets. 

ALLOPHANE. A mineral of a blue, 
and sometimes a green or brown colour, which 
occurs massive, or in imitative shapes. Lus- 



ALLOY. 



137 



ALLOY. 



tre vitreous ; fracture imperfectly conchoidal ; 
transparent or translucent on the edges. Mo- 
derately hard, but very brittle. Sp. gr. 1.89. 
Composition, silica 21.92, alumina 32.2, 
lime 0.73, sulphate of lime 0.52, carbonate 
of copper 3.06, hydrate of iron 0.27, water 
41.3. Stromeyer. It gelatinizes in acids. 
It is found in a bed of iron-shot limestone in 
greywacke slate, in the forest of Thuringia. 
It was called Riemannite. 

ALLAY or ALLOY. Where any pre- 
cious metal is mixed with another of less 
value, the assayers call the latter the alloy, 
and do not in general consider it in any other 
point of view than as debasing or diminishing 
the value of the precious metal. Philosophi- 
cal chemists have availed themselves of this 
term to distinguish all metallic compounds in 
general. Thus brass is called an alloy of cop- 
per and zinc ; bell-metal, an alloy of copper 
and tin. 

Alloys are not, as far as we know, definite- 
ly regulated like oxides in the proportions of 
their component parts. 100 parts of mercury 
will combine with 4 or 8 parts of oxygen, to 
form two distinct oxides, the black and the 
red ; but with no greater, less, or interme- 
diate proportions. But 100 parts of mercury 
will unite with 1, 2, 3, or with any quantity 
up to 100 or 1000, of tin or lead. The al- 
loys have the closest relations in their physi- 
cal properties with the metals. They are all 
solid at the temperature of the atmosphere, 
except some amalgams : they possess metallic 
lustre, even when reduced to a coarse pow- 
der ; are completely opaque, and more or less 
dense, according to the metals which compose 
them ; are excellent conductors of electricity ; 
crystallize more or less perfectly : some are 
brittle, others ductile and malleable; some 
have a peculiar odour; several are very sono- 
rous and elastic. When an alloy consists of 
metals differently fusible, it is usually mal- 
leable while cold, but brittle while hot ; as is 
exemplified in brass. 

The density of an alloy is sometimes great- 
er, sometimes less, than the mean density of 
its components, shewing, that, at the instant 
of their union, a diminution or augmentation 
of volume takes place. The relation between 
the expansion of the separate metals and that 
of their alloys, has been investigated only in 
a very few cases. Alloys containing a vola- 
tile metal are decomposed, in whole or in 
part, at a strong heat. This happens with 
those of arsenic, mercury, tellurium, and zinc. 
Those that consist of two differently fusible 
metals, may often be decomposed by expos- 
ing them to a temperature capable of melting 
only one of them. This operation is called 
eliquation. It is practised on the great scale 
to extract silver from copper. The argenti- 
ferous copper is melted with 3| times its 
weight of lead ; and the triple alloy is expos- 
ed to a sufficient heat. The lead carries off 



the silver in its fusion, and leaves the copper 
under the form of a spongy lump. The sil- 
ver is afterwards recovered from the lead by 
another operation. 

Some alloys oxidize more readily by heat 
and air, than when the metals are separately 
treated. Thus 3 of lead, and 1 of tin, at a 
dull red, burn visibly, and are almost instant- 
ly oxidized. Each by itself, in the same cir- 
cumstances, would oxidize slowly, and with- 
out the disengagement of light. 

The formation of an alloy must be regu- 
lated by the nature of the particular metals, 
to which therefore we refer. 

The degree of affinity between metals, may 
be in some measure estimated by the greater 
or less facility with which, when of different 
degrees of fusibility or volatility, they unite, 
or with which they can after union be sepa- 
rated by heat. The greater or less tendency 
to separate into different proportional alloys, 
by long continued fusion, may also give some 
information on this subject. Mr Hatchett 
remarked, in his admirable researches on me- 
tallic alloys, that gold made standard with 
the usual precautions by silver, copper, lead, 
antimony, &c. and then cast into vertical bars, 
was by no means an uniform compound ; but 
that the top of the bar, corresponding to the 
metal at the bottom of the crucible, contain- 
ed the larger proportion of gold. Hence, for 
thorough combination, two red-hot crucibles 
should be employed ; and the liquefied metals 
should be alternately poured from the one 
into the other. And to prevent unnecessary 
oxidizement by exposure to air, the crucibles 
should contain, besides the metal, a mixture 
of common salt and pounded charcoal. The 
melted alloy should also be occasionally stir- 
red up with a rod of pottery. 

The most direct evidence of a chemical 
change having taken place in the two metals 
by combination, is when the alloy melts at a 
much lower temperature than the fusing 
points of its components. Iron, which is 
nearly infusible, when alloyed with gold, ac- 
quires almost the fusibility of this metal. Tin 
and lead form solder, an alloy more fusible 
than either of its components ; but the triple 
compound of tin, lead, and bismuth, is most 
remarkable on this account. The analogy is 
here strong, with the increase of solubility 
which salts acquire by mixture, as is exem- 
plified in the uncrystallizable residue of saline 
solutions, or mother waters, as they are call- 
ed. Sometimes two metals will not directly 
unite, which yet, by the intervention of a 
third, are made to combine. This happens 
with mercury and iron, as has been shewn 
by Messrs Aikin, who effected this difficult 
amalgamation by previously uniting the iron 
to tin or zinc. 

The tenacity of alloys is generally, though 
not always, inferior to the mean of the sepa- 
rate metals. One part of lead will destroy 



ALLOY. 



138 



ALMONDS. 



the compactness and tenacity of a thousand 
of gold. Brass made with a small propor- 
tion of zinc, is more ductile than copper it- 
self; but when one-third of zinc enters into 
its composition, it becomes brittle. 

In common cases, the specific gravity af- 
fords a good criterion whereby to judge of 
the proportion in an alloy consisting of two 
metals of different densities. But a very fal- 
lacious rule has been given, in some respec- 
table works, for comparing the specific gra- 
vity that should result from given quantities 
of two metals of known densities alloyed to- 
gether, supposing no chemical penetration or 
expansion of volume to take place. Thus it 
has been taught, that if gold and copper be 
united in equal weights, the computed or ma- 
thematical specific gravity of the alloy is the 
arithmetical mean of the two specific gravi- 
ties. This error was pointed out by me in a 
paper published in the 7th number of the 
Journal of Science and the Arts; and the 
correct rule was at the same time given. The 
details belong to the article Specific Gravity ; 
but the rule merits a place here. The spe- 
cific gravity of the alloy is found by dividing 
the sum of the weights by the sum of the 
volumes, compared to water, reckoned unity. 
Or, in another form, the rule may be stated 
thus : Multiply the sum of the weights into 
the product of the two specific gravities for 
a numerator, and multiply each specific gra- 
vity into the weight of the other body, and 
add the two products together for a denomi- 
nator. The quotient obtained by dividing 
the numerator by the denominator, is the true 
computed mean specific gravity ; and that 
found by experiment, being compared with it, 
will shew whether expansion or condensation 
of volume has attended the chemical combi- 
nation. Gold having a specific gravity of 
19.36, and copper of 8.87, being alloyed in 
equal weights, give on the fallacious rule 
of the arithmetical mean of the densities, 
19.36+8.87 __ ^ u 

calculated mean specific gravity is only 12. 16. 
It is evident, that by comparing the former 
number with chemical experiment, we should 
be led to infer a prodigious condensation of 
volume beyond what really occurs. 

A circumstance was observed by Mr Hat- 
chett to influence the density of metals, which 
a priori might be thought unimportant. 
When a bar of gold was cast in a vertical 
position, the density of the metal at the lower 
end of the bar was greater than that of the 
top, in the proportion of 17.364 to 17.035. 
Are we to infer that melted metal is a com- 
pressible fluid, or rather, that particles pass- 
ing into the solid state under pressure, exert 
their cohesive attraction with adventitious 
strength ? Under the title Metal, a tabular 
view of metallic combinations will be found ; 
and under that of the particular metal, the 
requisite information about its alloys. 



ALLUVIAL FORMATIONS, in geo- 
logy, are recent deposits in valleys or in plains, 
of the detritus of the neighbouring mountains. 
Gravel, loam, clay, sand, brown coal, wood 
coal, bog iron ore, and calc tuff', compose the 
alluvial deposits. The gravel and sand some- 
times contain gold and tin, if the ores exist 
in the adjoining mountains. Petrified wood 
and animal skeletons are found in the allu- 
vial clays and sand. 

ALMANDINE. Precious garnet. 
ALMONDS. Sweet almonds are com- 
posed, by M. Boullay, of 

Water, - - - - 3.50 
Pellicle, - - v ., 5.00 

Fine oil, - - 54.00 

Albumen, - - - 24.00 
Liquid sugar, 6.00 

Gum, - -. .... -, 3.00 
Fibrous matter, 4.00 

Loss and acetic acid, 0.50 

100.00 

Bitter almonds consist, according to M. 
Vogel, of 

Envelope, - - 8.5 

Fat oil, - ... 28.0 
Caseous matter, 30.0 

Sugar, - 6.5 

Gum, - - - 3.0 

Vegetable fibre, 5.0 

Dense volatile oil, 
Prussic acid, - 

100.0 

The volatile oil, at first liquid, becomes 
solid, and crystallizes by contact with air : it 
communicates to water the taste and smell 
of hydrocyanic acid, without giving it the 
property of forming prussian blue with iron. 
Dogs on swallowing some of it instantly died. 
It is colourless, has an acrid burning taste, 
denser than water, very soluble in ether and 
alcohol, very inflammable, and consists in- 
deed of two quite distinct species of oil, 
which may be easily separated in distillation 
by apportioning the products. The least 
volatile is not poisonous, and experiences no 
alteration in azote, hydrogen, carbonic acid ; 
but with air or oxygen it speedily takes into 
a crystalline mass by oxidation. In this new 
state it reddens litmus, and continues to do 
so whatever purification it may receive. It 
is fusible, volatile, soluble in boiling water ; 
from which it falls down in crystals by cool- 
ing. It combines with alkalis, and may per- 
haps, from its several properties, be regarded 
as an acid. 

The more volatile oil does not solidify on 
contact with air ; it is so poisonous, that a 
very small dose of it kills animals in a few 
seconds. Alkalis have no action on it at 
ordinary temperature ; but when heated to- 
gether, an alkaline hydrocyanate is produc- 
ed, a crystallizable matter different from the 



ALTHEINE. 



139 



ALUMINA. 



above, and also an acid, and a resinous 
matter. 

ALOES. This is a hitter juice, extracted 
from the leaves of a plant of the same name. 
Three sorts of aloes are distinguished in the 
shops, by the names of aloe soccotrina, aloe 
hepatica, and aloe caballina. It is certain, 
however, that the different kinds are all pre- 
pared at Morviedro in Spain, from the same 
leaves of the common aloe. Deep incisions 
are made in the leaves, from which the juice 
is suffered to flow ; and this, after decanta- 
tion from its sediment, and inspissation in 
the sun, is exposed to sale in leathern bags 
by the name of soccotrine aloes. An addi- 
tional quantity of juice is obtained by pres- 
sure from the leaves ; and this, when decant- 
ed from its sediment and dried, is the hepatic 
aloes. And lastly, a portion of juice is ob- 
tained by strong pressure of the leaves, and 
is mixed with the dregs of the two preceding 
kinds to form the caballine aloes. The first 
kind is said to contain much less resin. The 
principal characters of good aloes are these : 
it must be glossy, not very black, but brown ; 
when rubbed or cut, of a yellow colour; 
compact, but easy to break ; easily soluble ; 
of an unpleasant peculiar smell, which can- 
not be described, and an extremely bitter 
taste. 

Aloes appears to be an intimate combina- 
tion of gummy resinous matter, so well blend- 
ed together, that watery or spirituous sol- 
vents, separately applied, dissolve the greater 
part of both. It is not determined whether 
there be any difference in the medical pro- 
perties of these solutions. Both are purga- 
tive, as is likewise the aloes in substance; 
and, if used too freely, are apt to prove heat- 
ing, and produce hemorrhoidal complaints. 

Braconnot imagines he has detected in 
aloes a peculiar principle, similar to the bit- 
ter resinous which Vauquelin has found in 
many febrifuge barks. The recent- juice of 
the leaves absorbs oxygen, and becomes a fine 
reddish-purple pigment. 

According to M. Liebeg, the bitter of aloes 
is plentifully obtained by the action of nitric 
acid of sp. gr. 1.25. This is the aloetic 
acid of M. Braconnot. With potash it forms 
a purple salt, which is but slightly soluble, 
which precipitates the salts of baryta, lead, 
and peroxide of iron, in flocks of a deep 
purple colour ; the protonitrate of mercury 
is precipitated of a light red. 

This substance, when purified, is the same 
with carbazotic acid, which see. The bitter 
of aloes is a compound of a peculiar sub- 
stance possessing the properties of the resins, 
and carbazotic acid. 

Wool, morphia, narcotine, and myrrh, 
yielded no carbazotic acid, when treated with 
nitric acid. 

ALTHEINE. The name of a supposed 
new vegetable principle, extracted from the 



roots of althea ojficinalis ; but it has been 
shewn to be identical with asparagin. 

ALUDEL. The process of sublimation 
differs from distillation in the nature of its 
product, which, instead of becoming con- 
densed in a fluid, assumes the solid state, 
and the form of the receivers may of course 
be very different. The receivers for subli- 
mates are of the nature of chimnies, in which 
the elastic products are condensed, and adhere 
to their internal surface. It is evident that 
the head of an alembic will serve very well 
to receive and condense such sublimates as 
are not very volatile. The earlier chemists 
thought proper to use a number of similar 
heads, one above the other, communicating 
in succession by means of a perforation in 
the superior part of each, which received the 
neck of the capital immediately above it. 
These heads, differing in no respect from the 
usual heads of alembics, excepting in their 
having no nose or beak, and in the other cir- 
cumstances here mentioned, were called alu- 
dels. They are seldom now to be seen in 
chemical laboratories, because the operations 
of this art may be performed with greater 
simplicity of instruments, provided attention 
be paid to the heat and other circumstances. 

ALUM. See ALUMINA (SULPHATE or). 

ALUM- EARTH. A massive mineral, 
of a blackish-brown colour, a dull lustre, an 
earthy and somewhat slaty fracture, sectile, 
and rather soft. By Klaproth's analysis it 
contains, charcoal 19.65, silica 40, alumina 
16, oxide of iron 6.4, sulphur 2.84, sulphates 
of lime and potash each 1.5, sulphate of iron 
1.8, magnesia and muriate of potash 0.5, and 
water 10.75. 

ALUM-SLATE. 1. Common. This 
mineral occurs both massive and in insulated 
balls of a greyish-black colour, dull lustre, 
straight slaty fracture, tubular fragments, 
streak coloured like itself. Though soft, it 
is not very brittle. Effloresces, acquiring the 
taste of alum. 

2. Glossy Alum-slate. A massive mineral 
of a bluish-black colour. The rents display 
a variety of lively purple tints. It has a 
semi-metallic lustre in the fracture, which is 
straight, slaty, or undulating. There is a 
soft variety of it, approaching in appearance 
to slate clay. By exposure to air its thick- 
ness is prodigiously augmented by the for- 
mation of a saline efflorescence, which sepa- 
rates its thinnest plates. These afterwards 
exfoliate in brittle sections, causing entire 
disintegration. 

ALUMINA. One of the primitive earths, 
which, as constituting the plastic principle of 
all clays, loams, and boles, was called argil 
or the argillaceous earth, but now, as being 
obtained in greatest purity from alum, is 
styled alumina. It was deemed elementary 
matter till Sir H. Davy's celebrated electro- 
chemical researches led to the belief of its 



ALUMINA. 



140 



ALUMINA. 



being, like baryta and lime, a metallic ox- 
ide. 

The purest native alumina is found in the 
oriental gems, the sapphire and ruby. They 
consist of nothing but this earth, and a small 
portion of colouring matter. The native 
porcelain clays or kaolins, however white and 
soft, can never be regarded as pure alumina. 
They usually contain fully half their weight 
of silica, and frequently other earths. To 
obtain pure alumina, we dissolve alum in 20 
times its weight of water, and add to it a 
little of the solution of carbonate of soda, to 
throw down any iron which may be present. 
We then drop the supernatant liquid into a 
quantity of the water of ammonia, taking care 
not to add so much of the aluminous solution 
as will saturate the ammonia. The volatile 
alkali unites with the sulphuric acid of the 
alum, and the earthy basis of the latter is sepa- 
rated in a white spongy precipitate. This 
must be thrown on a filter, washed, or edul- 
corated, as the old chemists expressed it, by 
repeated affusions of water, and then dried. 
Or if an alum, made with ammonia instead 
of potash, as is the case with some French 
alums, can be got, simple ignition dissipates 
its acid and alkaline constituents, leaving pure 
alumina. 

Alumina prepared by the first process is 
white, pulverulent, soft to the touch, adheres 
to the tongue, forms a smooth paste without 
grittiness in the mouth, insipid, inodorous, 
produces no change in vegetable colours, in- 
soluble in water, but mixes with it readily in 
every proportion, and retains a small quantity 
with considerable force ; is infusible in the 
strongest heat of a furnace, experiencing 
merely a condensation of volume and conse- 
quent hardness, but is in small quantities 
melted by the oxyhydrogen blowpipe. Its 
specific gravity is 2.000 in the state of pow- 
der, but by ignition it is augmented. 

Every analogy leads to the belief that alu- 
mina contains a peculiar metal, which may be 
called aluminum. The first evidences ob- 
tained of this position are presented in Sir H. 
Davy's researches. Iron negatively electri- 
fied by a very high power, being fused in con- 
tact with pure alumina, formed a globule 
whiter than pure iron, which effervesced 
slowly in water, becoming covered with a 
white powder. The solution of this in muri- 
atic acid, decomposed by an alkali, afforded 
alumina and oxide of iron. By passing pot- 
assium in vapour through alumina heated to 
whiteness, the greatest part of the potassium 
became converted into potash, which formed 
a coherent mass with that part of the alumina 
not decompounded ; and in this mass there 
were numerous grey particles, having the me- 
tallic lustre, and which became white when 
heated in the air, and which slowly effervesced 
in water. In a similar experiment made by 



the same illustrious chemist, a strong red heat 
only being applied to the alumina, a mass 
was obtained, which took fire spontaneously 
by exposure to the air, and which effervesced 
violently in water. This mass was probably 
an alloy of aluminum and potassium. The 
conversion of potassium into its oxide, dry 
potash, by alumina, proves the presence of 
oxygen in the latter. 

M. Woehler has discovered a method of 
preparing aluminum, founded on the inoxi- 
dability of this metal by water; and he 
makes chloride of aluminum, for the pur- 
pose of procuring the metal from it, by 
the following process. Alumina precipitated 
by excess of carbonate of potash, was well 
washed and dried, and then made into a 
thick paste with powdered charcoal, sugar, 
and oil : this paste was then heated in a 
covered crucible till all the organic matter 
was destroyed. By these means, any sub- 
stance is mixed very intimately with carbon. 
The product, while it was hot, was put into 
and made to fill a porcelain tube, which was 
placed in a furnace of an oblong form. One 
end of the tube was connected with another 
tube containing fused chloride of calcium, 
and this with an apparatus for the disengage- 
ment of chlorine : the other end of the tube 
opened into a small tubulated receiver, pro- 
vided with a conducting tube. When the 
apparatus was full of chlorine, the tube and 
its contents were made red-hot. The chlo- 
ride of aluminum was readily formed ; a 
small portion was carried over with oxide of 
carbon, which fumed strongly on coming 
into contact with the air. The chlorine was 
long retained by the mass of matter. The 
receiver contained chloride of aluminum in 
the state of powder. After an hour and a 
half, the chloride obstructed the end of the 
tube (although an inch in diameter) which 
passed into the receiver : this caused the 
stoppage -of the process. 

On taking the apparatus to pieces it was 
found, that all that part of the tube which 
passed through the furnace was filled with 
chloride of aluminum, and it weighed more 
than an ounce. It consisted partly of an 
aggregation of long crystals, and partly of a 
firm mass, of a pale yellowish-green colour, 
semitransparent, and of a lamellated and dis- 
tinctly crystalline texture. When brought 
into contact with the air, it fumed feebly, 
gave a smell of muriatic acid, and soon be- 
came a transparent fluid. When thrown 
into water, it dissolved with strong hissing, 
accompanied with so much heat, that the 
fluid, when its quantity is small, boils rapid- 
ly. Its fusing and vaporizing points appear 
to be the same. 

Chloride of aluminum may be preserved 
without any alteration in naphtha : when 
heated with this oil, it liquefies, and sinks to 



ALUMINA. 



141 



ALUMINA. 



the bottom of the vessel in the form of a 
reddish-brown liquid, upon which potassium 
exerts no action. 

When an attempt is made to heat chloride 
of aluminum with potassium in a tube, the 
action is so strong, and the extrication of heat 
is so considerable, that the apparatus is in- 
stantly broken. M. Woehler, therefore, em- 
ployed a small platina crucible, the cover of 
which was kept on by a wire of the same 
metal. At the moment of reduction, the 
crucible became intensely red-hot, both with- 
in and without, although it was but slightly 
heated : the metal of the crucible was not 
sensibly acted on. Some small pieces of 
potassium, of about the size of a pea, and not 
more than ten at once, are placed in the cru- 
cible, and upon them are put an equal num- 
ber of pieces of chloride of aluminum of the 
same size. The crucible is to be heated with 
the spirit-lamp, at first gently, and afterwards 
more strongly, and until the spontaneous in- 
candescence of the matter ceases. Excess 
of potassium is to be avoided ; for, after it 
was oxidized, it would dissolve a portion of 
the aluminum. The reduced mass is gene- 
rally completely fused, and is of a blackish- 
grey colour. When all is cold, the crucible 
is to be thrown into a large vessel of water : a 
grey powder is soon deposited, which, when 
looked at in the sunshine, appears to be 
entirely composed of small metallic plates. 
The powder is to be washed with cold water, 
and then dried. It is the metal of alumina. 

Aluminum somewhat resembles platinum 
in powder. Some small scaly coherent par- 
ticles were discerned, which had the colour 
and splendour of tin. Under the burnisher 
it readily assumes the appearance of this 
metal. Rubbed in an agate mortar, it seems 
to be a little compressible, and unites into 
larger scales, with a metallic lustre ; and it 
leaves in the mortar traces of a metallic ap- 
pearance. W'hen heated in the air till it is 
ignited, it inflames, and burns with great 
rapidity. The product is the white oxide 
of aluminum in a hard mass. Reduced to 
powder, and blown upon in the flame of a 
candle, each particle suddenly becomes an 
inflamed point, the splendour of which is 
not less than that of the sparks of iron 
burning in oxygen gas. In pure oxygen 
gas, aluminum burns with so dazzling a 
light that the eyes can scarcely bear it ; the 
heat generated is so considerable, that the 
oxide produced is partly fused. The par- 
ticles which have been fused are yellowish, 
and as hard as corundum ; they do not 
merely scratch, but they cut glass. In order 
that aluminum may burn in oxygen gas, it 
must be heated to redness. 

Aluminum is not oxidized by water ; and 
this fluid may spontaneously evaporate from 
the metal, without its being in the least tar- 
nished. When, however, the water is nearly 



at its boiling point, the metal is slowly oxi- 
dized, and hydrogen is liberated. 

Sulphuric and nitric acids, when cold, do 
not act upon aluminum : when heated, con- 
centrated sulphuric acid readily dissolves it, 
and without the disengagement of sulphurous 
acid. The sulphuric solution did not by 
evaporation give the smallest crystal of alum. 

Aluminum dissolves in even a weak solu- 
tion of caustic potash, with the evolution of 
hydrogen, and the same solution takes place 
in ammonia. 

When aluminum is heated to dull redness 
and exposed to a current of chlorine, it in- 
flames, and is converted into chloride, which 
sublimes as fast as it is formed. 

Sulphuret of aluminum is formed by let- 
ting sulphur drop upon aluminum in a state 
of vivid ignition. It is semi-metallic in ap- 
pearance, and, when polished, is of a shining 
iron-black colour. M. Woehler formed also 
the phosphuret, seleniuret, arseniuret, and 
telluret of aluminum. Hensman's Reper- 
toire de Chimie, Jan. 1828. 

When regarded as an oxide, Sir H. Davy 
estimates its oxygen and basis to be to one 
another as 15 to 33, or as 10 to 22. The 
prime equivalent of alumina would thus ap- 
pear to be 1.0+ 2.2= 3.2. 

But Berzelius's analysis of sulphate of alu- 
mina seems to indicate 2.136 as the ( quantity 
of the earth which combines with 5 of the 
acid. Hence aluminum will come to be re- 
presented by 2.136 1, = 1.136. We 
shall presently shew that his analysis, both of 
alum and sulphate of alumina, may be re- 
conciled nearly to Sir H. Davy's equivalent 
prime =. 3.2. That of aluminum will be- 
come of course 2.2. 

Alumina which has lost its plasticity by 
ignition, recovers it by being dissolved in an 
acid or alkaline menstruum, and then preci- 
pitated. In this state it is called a hydrate ; 
for when dried in a steam-heat it retains 
much water, and therefore resembles in com- 
position wavellite a beautiful mineral, con- 
sisting almost entirely of alumina, with about 
28 per cent of water. Alumina is widely 
diffused in nature. It is a constituent of 
every soil, and of almost every rock. It is 
the basis of porcelain, pottery, bricks, and 
crucibles. Its affinity for vegetable colouring 
matter is made use of in the preparation of 
lakes, and in the arts of dyeing and calico- 
printing. Native combinations of alumina 
constitute the fuller's earth, ochres, boles, 
pipe clays, &c. 

ALUMINA (SALTS OF). These salts 
have the following general characters: 

1. Most of them are very soluble in 
water, and their solutions have a sweetish 
acerb taste. 

2. Ammonia throws down their earthy 
base, even though they have been previously 
acidulated with muriatic acid. 



ALUMINA. 



142 



ALUM. 



3. At a strong red heat they give out a 
portion of their acid. 

4. Phosphate of ammonia gives a white 
precipitate. 

5. Hydriodate of potash produces a floc- 
culent precipitate of a white colour, passing 
into a permanent yellow. 

6. They are not affected by oxalate of am- 
monia, tartaric acid, ferroprussiate of potash, 
or tincture of galls. By the first two tests 
they are distinguishable from yttria, and by 
the last two from that earth and glucina. 

7. If bisulphate of potash be added to a 
solution of an aluminous salt, moderately con- 
centrated, octahedral crystals of alum will 
form. 

Acetate of Alumina. By digesting strong 
acetic acid on newly precipitated alumina, this 
saline combination can be directly formed. 
Vinegar of ordinary strength scarcely acts on 
the earth. But the salt is seldom made in 
this way. It is prepared in large quantities 
for the calico printers, by decomposing alum 
with acetate of lead ; or more economically 
with aqueous acetate of lime, having a specific 
gravity of about 1.050; a gallon of which, 
equivalent to nearly half a pound avoirdu- 
pois of dry acetic acid, is employed for every 
2% Ib. of alum. A sulphate of lime is formed 
by complex affinity, which precipitates, and 
an acetate of alumina floats above. The 
above proportion of alum is much beyond the 
equivalent quantity ; and the specific gravity 
of the liquid is consequently raised by the 
excess of salt. It is usually 1.080. By 
careful evaporation capillary crystals are 
formed, which readily deliquesce. M. Gay 
Lussac made some curious observations on 
the solutions of this salt. Even when made 
with cold saturated solutions of alum and 
acetate of lead, and consequently but little 
concentrated, it becomes turbid when heated 
to 122 Fahr. ; and at a boiling heat a preci- 
pitate falls of about one-half of the whole salt. 
On cooling it redissolved. This decomposi- 
tion by heat, which would be prejudicial to 
the calico printer, is prevented by the excess 
of alum which is properly used in actual 
practice. M. Gay Lussac thinks this phe- 
nomenon has considerable analogy with the 
coagulation of albumen by heat ; the particles 
of the water and of the solid matter being 
carried by the heat out of their sphere of ac- 
tivity, separate. It is probably a subacetate 
which falls down, as well as that which is ob- 
tained by drying the crystals. Wenzel's 
analysis of acetate of alumina gives 73.81 
acid to 26. 19 base, in 100 parts. If we sup- 
pose it to consist, like the sulphate, of three 
primes of acid to two of alumina, we shall 
have for its equivalent proportions, 20 of dry 
acid 4- 6.4 earth, or 75.8 -f 24.2 = 100. 
As alum contains, in round numbers, about 
l-9th of earthy base, 8 oz. of real acetic acid 
present in the gallon of the redistilled pyro- 



lignous, would require about 2| Ibs. of alum 
for exact decomposition. The excess em- 
ployed is found to be useful. 

The affinity between the constituents of 
this salt is very feeble. Hence the attraction 
of cotton fibre for alumina, aided by a mo- 
derate heat, is sufficient to decompose it. 

The following salts of alumina are insolu- 
ble in water: Arseniate, borate, phosphate, 
tungstate, mellate, saclactate, lithate, malate, 
camphorate. The oxalate is uncrystallizable. 
It consists of 56 acid and water, and 44 alu- 
mina. The tartrate does not crystallize. 
But the tartrate of potash and alumina is 
remarkable, according to Thenard, for yield- 
ing no precipitate, either by alkalis or alkaline 
carbonates. The supergallate crystallizes. 
There seems to be no dry carbonate. A 
supernitrate exists, very difficult to crystal- 
lize. Its specific gravity is 1.645. A mode- 
rate heat drives off the acid. The muriate 
is easily made by digesting muriatic acid on 
gelatinous alumina. It is colourless, astrin- 
gent, deliquescent, uncrystallizable, reddens 
turnsole, and forms a gelatinous mass by 
evaporation. Alcohol dissolves at 60 half 
its weight of this salt. A dull red heat se- 
parates the acid from the alumina. Its com- 
position is, according to Bucholz, 29.8 acid, 
30.0 base, 40.2 water, in 100 parts. 

Sulphate of alumina exists under several 
modifications. The simple sulphate is easily 
made, by digesting sulphuric acid on pure 
clay. The salt thus formed crystallizes in 
thin soft plates, having a pearly lustre. It 
has an astringent taste, and is so soluble in 
water as to crystallize with difficulty. When 
moderately heated the water escapes, and, at 
a higher temperature, the acid. Berzeiius 
has chosen this salt for the purpose of deter- 
mining the equivalent of alumina. He con- 
siders the dry sulphate as a compound of 100 
parts of sulphuric acid with 42.722 earth. 
This makes the equivalent 21.361, oxygen 
being reckoned 10, if we consider it a com- 
pound of a prime proportion of each. But 
if we regard it as consisting of 3 of acid 
and 2 of base, we shall have 32.0 for the 
prime equivalent of alumina. The reason for 
assigning this number will appear in treating 
of the next salt. 

ALUM. This important salt has been 
the object of innumerable researches both with 
regard to its fabrication and composition. 
It is produced, but in a very small quantity, 
in the native state, and this is mixed with he- 
terogeneous matters. It effloresces in various 
forms upon ores during calcination, but it 
seldom occurs crystallized. The greater part 
of this salt is factitious, being extracted from 
various minerals called alum ores ; such as, 
1. Sulphuretted clay. This constitutes the 
purest of all aluminous ores, namely, that of 
la Tolfa, near Civita Vecchia in Italy. It is 
white, compact, and as hard as indurated clay, 



ALUM. 



143 



ALUM. 



whence it is called petra aluminaris. It is 
tasteless and mealy. One hundred parts of 
this ore contain above forty of sulphur and 
fifty of clay, a small quantity of potash, and 
a little iron. Bergman says it contains 
forty-three of sulphur in one hundred, thirty- 
five of clay, and twenty-two of siliceous 
earth. This ore is first torrefied to acidify 
the sulphur, which then acts on the clay, and 
forms the alum. 

2. The pyritaceous clay, which is found at 
Schwemsal, in Saxony, at the depth of ten or 
twelve feet. It is a black and hard, but 
brittle substance, consisting of clay, pyrites, 
and bitumen. It is exposed to the air for 
two years; by which means the pyrites is 
decomposed, and the alum is formed. The 
alum ores of Hesse and Liege are of this 
kind; but they are first torrefied, which is 
said to be a disadvantageous method. 

3. The schistus aluminaris contains a va- 
riable proportion of petroleum and pyrites 
intimately mixed with it. When the last are 
in a very large quantity, this ore is rejected 
as containing too much iron. Professor Berg- 
man very properly suggested, that by adding 
a proportion of clay, this ore may turn out 
advantageously for producing alum. But 
if the petrol be considerable, it must be tor- 
refied. The mines of Becket in Normandy, 
and those of Whitbyin Yorkshire, are of this 
species. 

4. Volcanic aluminous ore. Such is that 
of Solfaterra near Naples. It is in the form 
of a white saline earth, after it has effloresced 
in the air ; or else it is in a stony form. 

5. Bituminous alum ore is called shale, 
and is in the form of a schistus, impregnated 
with so much oily matter, or bitumen, as to 
be inflammable. It is found in Sweden, and 
also in the coal mines at Whitehaven, and 
elsewhere. 

Chaptal fabricated alum on a large scale 
from its component parts. The purest and 
whitest clay being made into a paste with 
water, and formed into balls half a foot in 
diameter, these are calcined in a furnace, 
broken to pieces, and a stratum of the frag- 
ments laid on the floor. A due proportion 
of sulphur is then ignited in a chamber, in 
the same manner as for the fabrication of sul- 
phuric acid; and the fragments of burnt 
clay, imbibing this as it forms, begin after a 
few days to crack and open, and exhibit an 
efflorescence of sulphate of alumina. When 
the earth has completely effloresced, it is taken 
out of the chamber, exposed for some time 
in an open shed, that it may be the more in- 
timately penetrated by the acid, and is then 
lixiviated and crystallized in the usual man- 
ner. 

The most extensive alum manufactory in 
Great Britain is at Hurlett, near Paisley, on 
tho estate of the Earl of Glasgow. The next 
in magnitude is at Whitby : of whose state 



and processes an instructive account was pub- 
lished by Mr Winter in the 25th volume of 
Nicholson's Journal. The stratum of alu- 
minous schistus is about 29 miles in width, 
and it is covered by strata of alluvial soil, 
sandstone, ironstone, shell, and clay. The 
alum schist is generally found disposed in 
horizontal laminae. The upper part of the 
rock is the most abundant in sulphur ; so 
that a cubic yard taken from the top of the 
stratum is five times more valuable than the 
same bulk 100 feet below. 

If a quantity of the schistus be laid in a 
heap, and moistened with sea-water, it will 
take tire spontaneously, and will continue to 
burn till the whole inflammable matter be 
consumed. Its colour is bluish-grey. Its 
sp. grav. is 2.48. It imparts a bituminous 
principle to alcohol. Fused with an alkali, 
muriatic acid precipitates a large proportion 
of silex. 

The expense of digging and removing to a 
distance of 200 yards one cubic yard of the 
schistose rock, is about sixpence-halfpenny. 
A man can earn from 2s. Gd. to 3s. a-day. 
The rock, broken into small pieces, is laid on 
a horizontal bed of fuel, composed of brush- 
wood, &c. When about 4 feet in height of 
the rock is piled on, fire is set to the bottom, 
and fresh rock continually poured upon the 
pile. This is continued until the calcined 
heap be raised to the height of 90 or 100 feet. 
Its horizontal area has also been progressively 
extended at the same time, till it forms a 
great bed nearly 200 feet square, having about 
100,000 yards of solid measurement. The 
rapidity of the combustion is allayed by plas- 
tering up the crevices with small schist moist- 
ened. Notwithstanding of this precaution, a 
great deal of sulphuric or sulphurous acid is 
dissipated. 130 tons of calcined schist pro- 
duce on an average one ton of alum. This 
result has been deduced from an average of 
150,000 tons. 

The calcined mineral is digested in water 
contained in pits that usually contain about 
60 cubic yards. The liquid is drawn oft' into 
cisterns, and afterwards pumped up again 
upon fresh calcined mine. This is repeated 
until the specific gravity becomes 1. 15. The 
half-exhausted schist is then covered with wa- 
ter to take up the whole soluble matter. The 
strong liquor is drawn off into settling cis- 
terns, where the sulphate of lime, iron, and 
earth, are deposited. At some works the li- 
quid is boiled, which aids its purification. It 
is then run into leaden pans ten feet long, 
four feet nine inches wide, two feet two inches 
deep at the one end, and two feet eight inches 
at the other. This slope makes them be easily 
emptied. Here the liquor is concentrated at 
a boiling heat. Every morning the pans are 
emptied into a settling cistern, and a solution 
of muriate of potash, either pretty pure from 
the manufacturer^ or crude and compound 



ALUM. 



ALUM. 



from the soap-boiler, is added. The quantity 
of muriate necessary is determined by a pre- 
vious experiment in a basin, and is regulated 
for the workmen by the hydrometer. By this 
addition, the pan liquor, which had acquired 
a specific gravity of 1.4 or 1.5, is reduced to 
1.35. After being allowed to settle for two 
hours, it is run off into the coolers to be crys- 
tallized. At a greater sp. gravity than 1.35, 
the liquor, instead of crystallizing, would, 
when it cools, present us with a solid magma, 
resembling grease. Urine is occasionally 
added, to bring it down to the proper den- 
sity. 

After standing four days the mother waters 
are drained off, to be pumped into the pans 
on the succeeding day. The crystals of alum 
are washed in a tub, and drained. They are 
then put into a lead pan, with as much water 
as will make a saturated solution at the boil- 
ing point. Whenever this is effected, the so- 
lution is run off into casks. At the end often 
or sixteen days, the casks are unhooped and 
taken asunder. The alum is found exteriorly 
in a solid cake, but in the interior cavity in 
large pyramidal crystals, consisting of octa- 
edrons, inserted successively into one an- 
other. This last process is called roching. 
Mr Winter says, that 22 tons of muriate of 
potash will produce 100 tons of alum, to 
which 31 tons of the black ashes of the soap- 
boiler, or 73 of kelp, are equivalent. Where 
much iron exists in the alum ore, the alka- 
line muriate, by its decomposition, gives birth 
to an uncrystallizable muriate of iron. The 
alum manufactured in the preceding mode is 
a sulphate of alumina and potash. There is 
another alum which exactly resembles it'. 
This is a sulphate of alumina and ammonia. 
Both crystallize in regular octaedrons, formed 
by two four-sided pyramids joined base to 
base. Alum has an astringent sweetish taste. 
Its sp. gravity is about 1.71. It reddens 
the vegetable blues. It is soluble in 1 6 parts 
of water at 60, and in f ths of its weight at 
2 1 2. It effloresces superficially on exposure 
to air, but the interior remains long unchang- 
ed. Its water of crystallization is sufficient 
at a gentle heat to fuse it. If the heat be in- 
creased it froths up, and loses fully 45 per 
cent of its weight in water. The spongy re- 
sidue is called burnt or calcined alum, and is 
used by surgeons as a mild escharotic. A 
violent heat separates a great portion of its 
acid. 

Roman alum is crystallized in cubes, be- 
cause the solution from which the final crys- 
tals are obtained is never suffered to attain 
a higher temperature than 104 F. When 
this cubical alum is dissolved, and its solu- 
tion heated to temperatures above 110 F. 
a precipitate of sulphate of alumina is pro- 
duced, and the solution will now yield only 
octahedral crystals. Hence may be deduced 



the means of obtaining either cubical or octa- 
hedral alum at pleasure. 

Alum was thus analyzed by Berzelius: 1st, 
20 parts (grammes) of pure alum lost by the 
heat of a spirit-lamp 9 parts, which gives 45 
per cent of water. The dry salt was dissolv- 
ed in water, and its acid precipitated by the 
muriate of baryta; the sulphate of which, 
obtained after ignition, weighed 20 parts ; in- 
dicating in 100 parts 34.3 of dry sulphuric 
acid. 2d, Ten parts of alum were dissolved 
in water, and digested with an excess of am- 
monia. /Alumina, well washed and burnt, 
equivalent to 10.67 per cent, was obtained. 
In another experiment 10.86 per cent result- 
ed. 3d, Ten parts of alum dissolved in water 
were digested with carbonate of strontia, till 
the earth was completely separated. The sul- 
phate of potash, after ignition, weighed 1.815, 
corresponding to 0.981 potash, or, in 100 
parts, to 9.81. 

Alum, therefore, consists of 

Sulphuric acid, 34.33 
Alumina, 10.86 

Potash, 9.81 

Water, 45.00 

100.00 

or, Sulphate of alumina, 36.85 
Sulphate of potash, 18. 15 

Water, 45.00 

100.00 

Thenard's analysis, Ann. de Chimie, vol. 
58. or Nicholson's Journal, vol. 18. coincides 
perfectly with that of Berzelius in the product 
of sulphate of baryta. From 400 parts of 
alum he obtained 490 of the ignited barytic 
salt ; but the alumina was in greater propor- 
tion, equal to 12.54 per cent, and the sulphate 
of potash less, or 15.7 in 100 parts. 

Vauquelin, in his last analysis, found 48.58 
water ; and by Thenard's statement there are 
indicated 34.23 dry acid, 

7. 14 potash, 
12.54 alumina, 
46.09 water, 

100.00 

If we rectify Vauquelin's erroneous esti- 
mate of the sulphur of baryta, his analysis 
will also coincide with the above. Alum, 
therefore, differs from the simple sulphate of 
alumina previously described, which consisted 
of 3 prime equivalents of acid and 2 of earth, 
merely by its assumption of a prime of sul- 
phate of potash. It is probable that all the 
aluminous salts have a similar constitution. 
It is to be observed, however, that the num- 
ber 34.36 resulting from the theoretic pro- 
portions, is, according to Gilbert's remarks 
on the essay of Berzelius, the just representa- 
tion of the dry acid in 100 of sulphate of 
baryta, by another analysis, which makes the 
prime of baryta 9.57. 



ALUM. 



14-5 



ALUM. 



Should ammonia be suspected in alum, it 
may be detected, and its quantity estimated, 
by mixing quicklime with the saline solu- 
tion, and exposing the mixture to heat in a 
retort connected with a Woolfe's apparatus. 
The water of ammonia being afterwards sa- 
turated with an acid, and evaporated to a dry 
salt, will indicate the quantity of pure am- 
monia in the alum. A variety of alum, con- 
taining both potash and ammonia, may also 
be found. This will occur where urine has 
been used, as well as muriate of potash, in its 
fabrication. If any of these sulphates of alu- 
mina and potash be acted on, in a watery 
solution, by a gelatinous alumina, a neutral 
triple salt is formed, which precipitates in a 
nearly insoluble state. 

"When alum in powder is mixed with flour 
or sugar, and calcined, it forms the pyropho- 
rus of Homberg. 

Mr Winter first mentioned, that another 
variety of alum can be made with soda in- 
stead of potash. This salt, which crystallizes 
in octahedrons, has been also made with pure 
muriate of soda, and bisulphate of alumina, 
at the laboratory of Hurlett, by Mr W. Wil- 
son. It is extremely difficult to form, and 
effloresces like the sulphate of soda. 

On the subject of soda-alum I published 
a short paper in the Journal of Science for 
July 1822. The form and taste of this salt 
are exactly the same as those of common 
alum ; but it is less hard, being easily crushed 
between the fingers, to which it imparts an 
appearance of moisture. Its specific gravity 
is 1 .6. 100 parts of water at 60 F. dissolve 
110 of it; forming a solution, whose specific 
gravity is 1.296. In this respect, potash-alum 
is very different ; for 100 parts of water dis- 
solve only from eight to nine parts, forming 
a saturated solution, whose sp. gr. is no more 
than 1.0465. Its constituents are by my ana- 
lysis, 

Sulphuric acid, 34.00 4 primes, 33.96 
Alumina, 10.75 3 10.82 

Soda, 6.48 1 6.79 

Water, 49.00 25 48.43 

100.23 100.00 

Or it consists of three primes sulphate of alu- 
mina -|- one sulphate of soda. To each of 
the former five primes of water may be as- 
signed, and to the latter ten, as in Glauber's 
salt. 

The only injurious contamination of alum 
is sulphate of iron. It is detected by ferro- 
prussiate of potash. To get rid of it cheap- 
ly, M. Thenard recommended dissolving the 
alum in boiling water, and agitating the so- 
lution with rods as it cools. The salt is thus 
reduced to a fine granular powder, which 
being washed two or three times with cold 
water, and drained, yields a perfectly pure 
alum. For a very advantageous mode of 
concentrating alum liquors, as well as those 



of other salts, on the great scale, see EVA- 
PORATION. 

Mr Philips describes, in the 4th volume of 
the Annals of Philosophy, N. S. a new sul- 
phate of alumina, which he obtained by put- 
ting moist alumina into dilute sulphuric acid, 
and adding more occasionally, until it re- 
mained in excess. Being now filtered, a clear 
dense solution was obtained, which, when 
dropped into water, instantly let fall a preci- 
pitate almost as abundant as that from mu- 
riate of antimony. It also began to precipi- 
tate immediately, even of itself, though no 
tendency of this kind was observed as long 
as the excess of alumina remained mixed 
with it. The deposition went on for several 
months ; but the clear part was always pre- 
cipitable by water. Another property of this 
sulphate of alumina is, that, if heated to 160 
or 170 Fahr. it becomes opaque and thick, 
but, upon cooling, in a few days it becomes 
clear again. Mr Philips considers the num- 
ber 27 as representing the atom of alumina 
to hydrogen = 1 ; and the above salt as con- 
sisting of two atoms sulphuric acid = 40 X 
2 = 80 + 3 atoms alumina = 27 X 3 = 
81 ; or, on the oxygen scale, of 2 X 5 = 10 
acid -f 3.375 X 3 = 10. 125 alumina. 

Alum is used in large quantities in many 
manufactories. When added to tallow, it ren- 
ders it harder. Printers' cushions, and the 
blocks used in the calico manufactory, are 
rubbed with burnt alum to remove any 
greasiness, which might prevent the ink or 
colour from sticking. Wood sufficiently soak- 
ed in a solution of alum, does not easily take 
fire ; and the same is true of paper impreg- 
nated with it, which is fitter to keep gun- 
powder, as it also excludes moisture. Paper 
impregnated with alum is useful in whitening 
silver, and silvering brass without heat. Alum 
mixed in milk helps the separation of its but- 
ter. If added in a very small quantity to 
turbid water, in a few minutes it renders it 
perfectly limpid, without any bad taste or 
quality ; while the sulphuric acid imparts to 
it a very sensible acidity, and does not preci- 
pitate so soon, or so well, the opaque earthy 
mixtures that render it turbid, as I have often 
tried. It is used in making pyrophorus, in 
tanning, and many other manufactures, par- 
ticularly in the art of dyeing, in which it is 
of the greatest and most important use, by 
cleansing and opening the pores on the sur- 
face of the substance to be dyed, rendering it 
fit for receiving the colouring particles, (by 
imparting alumina to the stuff), and in this 
way making the colour fixed. Crayons gene- 
rally consist of the earth of alum, finely pow- 
dered, and tinged for the purpose. In me- 
dicine it is employed as an astringent. 

M. Hollunder states, that solution of alu- 
mina in nitric acid is readily decomposed by 
the influence of the atmosphere, even at 
K 



AMBER. 



14-6 



AMBER. 



ordinary temperatures, although elevation of 
temperature increases the effect It is most 
rapid when free acid is present. The floc- 
culent substance precipitated is supposed to 
be aluminum, oxidized to a higher degree 
than the alumina obtained by the ordinary 
process ; for, at the same time, the nitric acid 
undergoes decomposition, and the oxide ob- 
tained is much more insoluble than ordinary 
alumina. 

ALUMINITE. A mineral of a snow- 
white colour, dull, opaque, and having a fine 
earthy fracture. It has a glistening streak. 
It is found in kidney-shaped pieces, which 
are soft to the touch, and adhere slightly to 
the tongue. Sp. gravity 1.67. 
It consists of sulphuric acid, 19.25 

Alumina, 32.56 

Water, 47.00 

Silica, lime, and oxide of irpn, 1.25 

100.00 

The above alum ore is found chiefly in the 
alluvial strata round Halle in Saxony. 

AMADOU. It is a variety of the boletus 
igniarius, found on old ash and other trees. 
It is boiled in water to extract its soluble 
parts, then dried and beat with a mallet to 
loosen its texture. It has now the appear- 
ance of very spongy doe-skin leather. It is 
lastly impregnated with a solution of nitre, 
and dried, when it is called spunk, or Ger- 
man tinder ; a substance much used on the 
Continent for lighting fires, either from the 
collision of flint and steel, or from the sud- 
den condensation of air in the atmospheric 
pyrophore. 

AMALGAM. This name is applied to 
the combinations of mercury with other me- 
tallic substances. See MERCURY, and ORES 
OF MERCURY. 

AMBER is a hard, brittle, tasteless sub- 
stance, sometimes perfectly transparent, but 
mostly semitransparent or opaque, and of a 
glossy surface. It is found of all colours, but 
chiefly yellow or orange, and often contains 
leaves or insects. Its specific gravity is from 
1.065 to 1. 100 ; its fracture is even, smooth, 
and glossy ; it is capable of a fine polish, and 
becomes electric by friction ; when rubbed or 
heated, it gives a peculiar agreeable smell, 
particularly when it melts, that is at 550 of 
Fahrenheit, but then it loses its transparen- 
cy : projected on burning coals, it burns with 
a whitish flame, and a whitish-yellow smoke, 
but gives very little soot, and leaves brownish 
ashes. It is insoluble in water and alcohol, 
though the latter, when highly rectified, ex- 
tracts a reddish colour from it ; but it is so- 
luble in the sulphuric acid, which then ac- 
quires a reddish-purple colour, and is preci- 
pitable from it by water. No other acid dis- 
solves it, nor is it soluble in essential or ex- 
pressed oils, without some decomposition and 
long digestion ; but pure alkali dissolves it. 



By distillation it affords a small quantity of 
water, with a little acetic acid, an oil, and a 
peculiar acid. See ACID (SucciNic). The 
oil rises at first colourless ; but, as the heat 
increases, becomes brown, thick, and empy- 
reumatic. The oil may be rectified by suc- 
cessive distillations, or it may be obtained 
very light and limpid at once, if it be put 
into a glass alembic with water, as the elder 
Rouelle directs, and distilled at a heat not 
greater than 212 Fahr. It requires to be 
kept in stone bottles, however, to retain this 
state ; for in glass vessels it becomes brown 
by the action of light. 

Amber is met with plentifully in regular 
mines in some parts of Prussia. The upper 
surface is composed of sand, under which is 
a stratum of loam, and under this a bed of 
wood, partly entire, but chiefly mouldered or 
changed into a bituminous substance. Un- 
der the wood is a stratum of sulphuric or ra- 
ther aluminous mineral, in which the amber 
is found. Strong sulphurous exhalations are 
often perceived in the pits. 

Detached pieces are also found occasion- 
ally on the sea-coast in various countries. It 
has been found in gravel beds near London. 
In the Royal Cabinet at Berlin there is a 
mass of 18 Ibs. weight, supposed to be the 
largest ever found. Jussieu asserts, that the 
delicate insects in amber, which prove the 
tranquillity of its formation, are not Euro- 
pean. M. Hau'y has pointed out the follow- 
ing distinctions between mellite and copal, 
the bodies which most closely resemble am- 
ber. Mellite is infusible by heat : A bit of 
copal heated at the end of a knife takes fire, 
melting into drops, which flatten as they fall : 
whereas amber burns with spitting and froth- 
ing ; and when its liquefied particles drop, 
they rebound from the plane which receives 
them. The origin of amber is at present in- 
volved in perfect obscurity, though the ra- 
pid progress of vegetable chemistry promises 
soon to throw light on it. Various frauds 
are practised with this substance. Neumann 
states as the common practices of workmen 
the two following : The one consists in sur- 
rounding the amber with sand in an iron pot, 
and cementing it with a gradual fire for forty 
hours, some small pieces placed near the sides 
of the vessel being occasionally taken out for 
judging of the effect of the operation. The 
second method, which he says is that most ge- 
nerally practised, is by digesting and boiling 
the amber about twenty hours with rape- 
seed oil, by which it is rendered both clear 
and hard. 

Werner has divided it into two sub-species, 
the white and the yellow ; but there is little 
advantage in the distinction. Its ultimate 
constituents are carbon, hydrogen, and oxy- 
gen. Although my experiments on the ulti- 
mate analysis of amber were conducted care- 
fully, with re-trituration and re-ignition, no 



AMBERGRIS. 



14-7 



AMBERGRIS. 



good atomic configuration of it occurred to 
me. It yielded, in 100 parts, 70.68 carbon, 
11.62 hydrogen, and 17.77 oxygen; or of 
the elements of water 20 -f- hydrogen in ex- 
cess 9.4, independently of the carbon. Phil. 
Trans. 1822. 

In the second volume of the Edinburgh 
Philosophical Journal, Dr Brewster has given 
an account of some optical properties of am- 
ber, from which he considers it established 
beyond a doubt that amber is an indurated 
vegetable juice ; and that the traces of a re- 
gular structure, indicated by its action upon 
polarized light, are not the effect of the ordi- 
nary laws of crystallization by which mellite 
has been formed, but are produced by the 
same causes which influence the mechanical 
condition of gum-arabic, and other gums, 
which are known to be formed by the succes- 
sive deposition and induration of vegetable 
fluids. 

M . Berzelius adopts the opinion that am- 
ber is of vegetable origin ; that, like ordinary 
resins, it has flowed from vegetables in the 
state of a balsam, and has afterwards acquir- 
ed hardness gradually. Amber, according to 
this eminent chemist, contains five substan- 
ces: 1. An odoriferous oil, in small quan- 
tity. 2. A yellow resin intimately combined 
with this oil, dissolving freely in alcohol, 
ether, and alkalis, very fusible, and resem- 
bling ordinary vegetable resins. 3. A resin 
soluble with difficulty in cold alcohol, more 
freely in hot alcohol, from which it separates 
on cooling as a white powder soluble in ether 
and alkalis. These two resins and the vola- 
tile oil, if removed from amber by ether, and 
then obtained by evaporation of the latter in 
water, form a natural viscid balsam, very 
odorous, of a clear yellow colour, and which 
gradually becomes hard, but retains some 
odour. There is every reason for supposing 
this to be precisely the substance from which 
amber originates, but, at the same time, ra- 
ther poorer in essential oil than at first ; and 
that the insoluble substances in amber have 
been gradually formed by a spontaneous al- 
teration of this balsam, but at the same time 
have enveloped one part of it, and so pre- 
served it from entire decomposition or change. 
4. Succinic acid dissolved with the preceding 
bodies by ether, alcohol, and alkalis. 5. A 
body insoluble in alcohol, ether, and alkalis, 
analogous in some points to the substance 
found by Dr John in lac, and called by him 
the principle of lac. This is formed in large 
quantity when a solution of lac in alkali is 
precipitated by chlorine. 

Amber is also used in varnishes. See 
VARNISH, and OIL of AMBER. 

AMBERGRIS is found in the sea, near 
the coasts of various tropical countries ; and 
has also been taken out of the intestines of 
the physeter macrocephalus, the spermaceti 
whale. As it has not been found in any 



whales but such as are dead or sick, its pro- 
duction is generally supposed to be owing to 
disease, though some have a little too per- 
emptorily affirmed it to be the cause of the 
morbid affection. As no large piece has ever 
been found without a greater or less quan- 
tity of the beaks of the sepia octopodia, the 
common food of the spermaceti whale, inter- 
spersed throughout its substance, there can 
be little doubt of its originating in the in- 
testines of the whale ; for if it were occasion- 
ally swallowed by it only, and then caused 
disease, it must much more frequently be 
found without these, when it is met with 
floating in the sea, or thrown upon the shore. 

Ambergris is found of various sizes, gene- 
rally in small fragments, but sometimes so 
large as to weigh near two hundred pounds. 
When taken from the whale it is not so hard 
as it becomes afterward on exposure to the 
air. Its specific gravity ranges from 780 to 
926. If good, it adheres like wax to the edge 
of a knife with which it is scraped, retains the 
impression of the teeth or nails, and emits a 
fat odoriferous liquid on being penetrated 
with a hot needle. It is generally brittle ; 
but, on rubbing it with the nail, it becomes 
smooth like hard soap. Its colour is either 
white, black, ash-coloured, yellow, or black- 
ish; or it is variegated, namely, grey with 
black specks, or grey with yellow specks. Its 
smell is peculiar, and not easy to be counter- 
feited. At 144 it melts, and at 212 is vola- 
tilized in the form of a white vapour. But 
on a red-hot coal it burns, and is entirely dis- 
sipated. Water has no action on it ; acids, 
except nitric, act feebly on it; alkalis com- 
bine with it, and form a soap ; ether and the 
volatile oils dissolve it ; so do the fixed oils, 
and also ammonia, when assisted by heat; 
alcohol dissolves a portion of it, and is of 
great use in analyzing it, by separating its 
constituent parts. According to Bouillon la 
Grange, who has given the latest analysis of 
it, 3820 parts of ambergris consist of adipo- 
cere 2016 parts, a resinous substance 1167, 
benzoic acid 425, and coal 212. But Bu- 
cholz could find no benzoic acid in it. I 
examined two different specimens with con- 
siderable attention. The one yielded ben- 
zoic acid, the other, equally genuine to all 
appearance, afforded none. See ADIPOCERE, 
and INTESTINAL CONCRETION. 

An alcoholic solution of ambergris, added 
in minute quantity to lavender water, tooth 
powder, hair powder, wash balls, &c. com- 
municates its peculiar fragrance. Its retail 
price being in London so high as a guinea 
per oz. leads to many adulterations. These 
consist of various mixtures of benzoin, lab- 
danum, meal, &c. scented with musk. The 
greasy appearance and smell which heated 
ambergris exhibits, afford good criter ia, joined 
to its solubility in hot ether and alcohol. 

It has occasionally been employed in me- 



AMETHYST. 



148 



AMMONIA. 



dicine, but its use is now confined to the 
perfumer. Dr Swediaur took thirty grains 
of it without perceiving any sensible effect. 

AMBLYGONITE. A greenish-coloured 
mineral of different pale shades, marked on 
the surface with reddish and yellowish-brown 
spots. It occurs massive and crystallized in 
oblique four-sided prisms. Lustre vitreous ; 
cleavage parallel with the sides of an oblique 
four-sided prism of 106 10/ and 77 5(X; 
fracture uneven ; fragments rhomboidal ; 
translucent; hardness, as felspar; brittle; 
sp. gr. 3.0: intumesces with the blowpipe, 
and fuses with a reddish-yellow phosphores- 
cence into a white enamel. It occurs in 
granite, along with green topaz and tourma- 
line, near Pinig in Saxony. It seems to be 
a species of spodumene. 

AMBREINE. By digesting ambergris 
in hot alcohol, sp. gr. 0.827, the peculiar sub- 
stance called ambreine by Pelletier and Ca- 
ventou is obtained. The alcohol, on cooling, 
deposits the ambreine in very bulky and irre- 
gular crystals, which still retain a very con- 
siderable portion of alcohol. Thus obtained, 
it has the following properties: It is of a 
brilliant white colour, has an agreeable odour, 
of which it is deprived by repeated solutions 
and crystallizations. It is destitute of taste, 
and does not act on vegetable blues. It is 
insoluble in water, but dissolves readily in 
alcohol and ether ; and in much greater 
quantity in these liquids when hot, than 
when cold. It melts at the temperature of 
86, softening at 77. It is partly volati- 
lized and decomposed into a white smoke 
when heated above 212. It does not seem 
capable of combining with an alkali, or of 
being saponified. When heated with nitric 
acid, it becomes green and then yellow, while 
nitrous gas is exhaled. By this absorption 
of oxygen it is converted into an acid, which 
has been called ambreic acid. This acid is 
yellowish-white, has a peculiar smell, reddens 
vegetable blues, does not melt at 212, and 
evolves no ammonia when decomposed at 
higher temperatures. It is soluble in alco- 
hol and ether ; but slightly so in water. Am- 
breate of potash gives yellow precipitates with 
muriate of lime, muriate of baryta, sulphate 
of copper, sulphate of iron, nitrate of silver, 
acetate of lead, corrosive sublimate, 'muriate 
of tin, and muriate of gold. Journ. de 
Pharm. v. 49. 

AMETHYST. The amethyst is a gem 
of a violet colour, and great brilliancy, said 
to be as hard as the ruby or sapphire, from 
which it only differs in colour. This is 
called the oriental amethyst, and is very rare. 
When it inclines to the purple or rosy colour, 
it is more esteemed than when it is nearer to 
the blue. These amethysts have the same 
figure, hardness, specific gravity, and other 
qualities, as the best sapphires or rubies, and 
come from the same places, particularly from 



Persia, Arabia, Armenia, and the West In- 
dies. The occidental amethysts are merely 
coloured crystals or quartz. See QUARTZ, 
and SAPPHIRE. 

AMI ANTHOIDE. A mineral, in long 
capillary filaments, of an olive-green colour, 
flexible and elastic. Lustre, brilliant silky. 
It is composed of silica 47, lime 1 1, mag- 
nesia 7, oxide of iron 20, manganese 10. 
Vauquelin. It is found at Oisans in France. 
Philips 's Mineralogy. 

AMIANTHUS. Mountain flax. See 

ASBESTUS. 

AMIATITE. FIORITE, or PEARL-SIN- 
TER. 

AMIDINE. This is a substance pro- 
duced, according to M. de Saussure, when 
we abandon the paste of starch to itself, at 
the ordinary temperature, with or without 
the contact of air. See STARCH. 

AMMONIA. Called also volatile alkali. 
We shall first consider this substance in its 
purely scientific relations, and then detail its 
manufacture on the great scale, and its uses 
in the arts. There is a saline body, formerly 
brought from Egypt, where it was separated 
from soot by sublimation, but which is now 
made abundantly in Europe, called sal am- 
moniac. From this salt pure ammonia can 
be readily obtained by the following process : 
Mix unslacked quicklime with its own weight 
of sal ammoniac, each in fine powder, and 
introduce them into a glass retort. Join to 
the beak of the retort, by a collar of caout- 
chouc, (a neck of an India rubber bottle 
answers well), a glass tube about 18 inches 
long, containing pieces of ignited muriate of 
lime. This tube should lie in a horizontal 
position, and its free end, previously bent 
obliquely by the blowpipe, should dip into 
dry mercury in a pneumatic trough. A slip 
of porous paper, as an additional precaution, 
may be tied round the tube, and kept moist 
with ether. If a gentle heat from a charcoal 
chauffer or lamp be now applied to the bot- 
tom of the retort, a gaseous body will bubble 
up through the mercury. Fill a little glass 
tube, sealed at one end, with the gas, and 
transfer it, closely stopped at the other end, 
into a basin containing water. If the water 
rise instantly and fill the whole tube, the gas 
is pure, and may be received for examina- 
tion. 

Ammonia is a transparent, colourless, and 
consequently invisible gas, possessed of elas- 
ticity, and the other mechanical properties of 
the atmospherical air. Its specific gravity is 
an important datum in chemical researches, 
and has been rather differently stated. Yet, 
as no aeriform body is more easily obtained 
in a pure state than ammonia, this diversity 
among accurate experimentalists shews the 
nicety of this statical operation. MM. Biot 
and Arago make it= 0.59669 by experi- 
ment, and by calculation from its elementary 



AMMONIA. 



149 



AMMONIA. 



they make it = 0.59438. Kirwan 
says, that 100 cubic inches weigh 18.16 gr. 
at 30 inches of bar. and 61 F. which, com- 
pared to air reckoned 30.519, gives 0.59540. 
Sir H. Davy determines its density to be = 
0.590, with which estimate the theoretic cal- 
culations of Dr Front, in the 6th volume of 
the Annals of Philosophy, agree. 

This gas has an exceedingly pungent smell, 
well known by the old name of spirits of 
hartshorn. An animal plunged into it spee- 
dily dies. It extinguishes combustion, but 
being itself to a certain degree combustible, 
the flame of a taper immersed in it is en- 
larged before going out. By exposing this 
gas to a very low temperature M. Bussy suc- 
ceeded in liquefying it. See ACID ( SULPHU- 
ROUS). It has a very acrid taste. Water con- 
denses it very rapidly. The following valu- 
able table of its aqueous combinations has 
been given by Sir H. Davy. 



Ammonia. 


Water. 


22.07 


77.93 


19.54 


80.46 


17.52 


82.48 


15.88 


84.12 


14.53 


85.47 


13.46 


86.54 


12.40 


87.60 


11.56 


88.44 


10.82 


89.18 


10.17 


89.83 


9.60 


90.40 


9.50 


90.50 



Sp. Gr. 
0.8750 
0.8875 
0.9000 
0.9054 



Ammonia. 
32.50 
29.25 
26.00 
25.37 



Water. 
67.50 
70.75 
74.00 
74.63 



Sp. Gr. 
0.9166 
0.9255 
0.9326 
0.9385 
0.9435 
0.9476 
0.9513 
0.9545 
0.9573 
0.9597 
0.9619 
0.9692 



Water is capable of dissolving easily about 
one-third of its weight of ammoniacal gas, or 
460 times its bulk. Hence, when placed in 
contact with a tube filled with this gas, water 
rushes into it with explosive velocity. Pro- 
bably the quantity of ammonia stated in 
the above table is too high by about one per 
cent. 

The following table of the quantity of am- 
monia in 100 parts, by weight, of its aqueous 
combinations at successive densities, was pub- 
lished by me in the Philosophical Magazine 
for March 1821. 



Water 
of 

0.900. 


Ammo- 
nia in 
100. 


Water 
in 
100. 


Sp. gr. 
by expe- 
riment. 


Mean 
specific 
gravity. 


Equivalent primes. 


100 


26.500 


73.500 


0.9000 






95 


25.175 


74.825 


0.9045 


0.90452 


Wat. Am. 


90 


23.850 


76.150 


0.9090 


0.90909 


24 + 76, 6 to 1 


85 


22.525 


77.475 


0.9133 


0.91370 




80 


21.200 


78.800 


0.9177 


0.91838 


21.25 + 78.75, 7 to 1 


75 


19.875 


80.125 


0.9227 


0.92308 




70 


18.550 


81.450 


0.9275 


0.92780 


19.1 + 80.9, 8 to I 


65 


17.225 


82.775 


0.9320 


0.93264 


17.35 + 82.65, 9 to 1 


60 


15.900 


84.100 


0.9363 


0.93750 


15.9+84.1, 10 to 


55 


14.575 


85.425 


0.9410 


0.94241 


14.66 + 85.34, 11 to 


50 


13.250 


86.750 


0.9455 


0.94737 


13.60 + 86.40, 12 to 


45 


11.925 


88.075 


0.9510 


0.95238 


11.9 + 88.1, 14 to 


40 


10.600 


89.400 


0.9564 


0.95744 


11.2+88.8, 15 to 


35 


9.275 


90.725 


0.9614 


0.96256 




30 


7.950 


92.050 


0.9662 


0.96774 


8.63 + 91.37, 20 to 1 


25 


6.625 


93.375 


0.9716 


0.97297 


7 + 93, 25 to 1 


20 


5.300 


94.700 


0.9768 


0.97826 


6 + 94, 30 to 1 


15 


3.975 


96.025 


0.9828 


0.98360 


4.5 + 95.5, 40 to 1 


10 


2.650 


97.350 


0.9887 


0.9890 


3 + 97, 60 to 1 


5 


1.325 


98.675 


0.9945 


0.99447 





The remarkable expansiveness which am- 
monia carries into its first condensation with 
water, continues in the subsequent dilutions 
of its aqueous combinations. This curious 
property is not peculiar to pure ammonia, but 
belongs, as I have found, to some of its salts. 
Thus sal ammoniac, by its union with water, 
causes an enlargement of the total volume of 
the compound, beyond the volume of the con- 
stituents of the solution. Or the specific gra- 
vity of the saturated solution is less than the 
mean sp. gravity of the salt and water. I 



know of no salts with which this phenomenon 
occurs, except the ammoniacal. 

Near the two extremities of the table, the 
experimental and computed specific gravities 
agree ; the reciprocal affinity thus balancing 
the peculiar expansiveness communicated by 
the ammonia, which becomes conspicuous in 
the intermediate proportions of water and gas. 
This fact is in unison with the general laws 
of chemical combination. 

Since 73.5 grains of distilled water exist 
in 100 water of ammonia, specific gravity 



AMMONIA. 



150 



AMMONIA. 



0.900, which occupy the volume of 1.111, 
one part of water in bulk will be converted 
into almost exactly one and a half of such 
water of ammonia. 100 grains of this water 
contain 147.2 cubic inches of gas. Hence 
one grain of water holds condensed in such 
aqueous ammonia 2 cubic inches of the gas, 
or one volume of distilled water is united to 
505 volumes of the gas. 

It deserves to be remarked, that one vo- 
lume of water, when converted into aqueous 
muriatic acid, specific gravity 1.200, or into 
aqueous ammonia, sp. gr. 0.900, expands in 
either case into a volume and a half. 

If from 998 we deduct the specific gravity 
of water of ammonia, expressed in three in- 
tegers, the remainder, divided by 4, will give 
a quotient representing the quantity of real 
alkali present. This rule is exact for all such 
liquid ammonia as is commonly used in che- 
mical researches and in medicine, viz. be- 
tween sp. grav. 936 and 980, water being 
1000. 

Liquid ammonia, as the aqueous compound 
is termed, may therefore, like spirits, be very 
accurately valued by its specific gravity. But 
it differs remarkably from alcoholic mixtures 
in this respect, that the strongest ammoniacal 
liquor, when it is diluted with water, suffers 
little condensation of volume. The specific 
gravity of the dilute, is not far from that of 
its components. Hence having one point 
accurately, we can compute all below it, by 
paying attention to the rule given under SPE- 
CIFIC GRAVITY. To procure aqueous ammo- 
nia, we may use either a common still and 
refrigeratory, or a Woolfe's apparatus. The 
latter should be preferred. Into a retort we 
put a mixture of two parts of slacked lime, 
and one part of pulverized sal ammoniac, 
and having connected the beak of the retort 
with the Woolfe's apparatus, containing pure 
water, we then disengage the ammonia by 
the application of heat. When gas ceases to 
be. evolved, the addition of a little hot water 
will renew its disengagement, and ensure 
complete decomposition of the salt. Since 
sal ammoniac contains nearly ^ its weight of 
ammonia, ten pounds of it should yield by 
economical treatment 30 pounds of liquid, 
whose specific gravity is 0.950, which is as 
strong as the ordinary purposes of chemistry 
and medicine require ; and it will form twice 
that quantity, or 60 pounds of the common 
water of ammonia sold by apothecaries, which 
has rarely a smaller density than 0.978 or 
0.980. There is no temptation to make it 
with the ammoniacal carbonate ; but if this 
salt be accidentally present, it is instantly 
detected by its causing a milkiness in lime 
water. 

Ammoniacal gas, perfectly dry when mix- 
ed with oxygen, explodes with the electric 
spark, and is converted into water and nitro- 
gen, as has been shewn in an ingenious paper 



by Dr Henry. But the simplest, and per- 
haps most accurate mode of resolving ammo- 
nia into its elementary constituents, is that 
first practised by M. Berthollet, the celebrat- 
ed discoverer of its composition. This con- 
sists in making the pure gas traverse very 
slowly an ignited porcelain tube of a small 
diameter. The process, as lately repeated by 
M. Gay Lussac, yielded, from 100 cubic 
inches of ammonia, 200 cubic inches of con- 
stituent gases ; of which, by subsequent ana- 
lysis, 50 were found to be nitrogen, and 150 
hydrogen. Hence we see, that the recipro- 
cal affinity of the ammoniacal elements had 
effected a condensation equal to one-half of 
the volume of the free gases. It appears by 
the most recent determinations, that the spe- 
cific gravity of hydrogen is 0.0694, compar- 
ed to air as unity, and that of nitrogen 0. 9722. 
Three volumes of the former will therefore 
weigh 0.2082, and one of the latter, 0.9722 ; 
the sum of which numbers, 1.1804, divided 
by 2, ought to coincide with the experimental 
density of ammonia. Now, it is 0.5902, 
being an exact correspondence. And the 
ratio of the two weights, reduced to 100 
parts, will be 82.36 nitrogen to 17.64 hydro- 
gen. To reduce ammonia to the system of 
equivalents, or to find its saturating ratio on 
that scale where oxygen represents unity, we 
have this proportion ; 9722 : 1.75 : : 1. 1804 : 
2. 125 ; so that 2. 125 may be called its prime 
equivalent. We shall find this number de- 
duced from analysis, confirmed by the syn- 
thesis of all the ammotiiacal salts. 

Dr Prout, in an able memoir on the rela- 
tion between the specific gravities of gaseous 
bodies and the weights of their atoms, pub- 
lished in the 6th vol. of the Annals of Phi- 
losophy, makes the theoretical weight of the 
atom of ammonia to be only 1.9375, consi- 
dering it as a compound of 1 atom of azote, 
and 1^ atoms of hydrogen. This statement 
appears to be a logical inference from Mr 
Dalton's hypothesis of atomical combination. 
For water, the main groundwork of his ato- 
mic structure, is represented as a compound 
of one atom of oxygen with one atom of hy- 
drogen ; and this atomical unit of hydrogen 
consists of two volumes of the gas. Hence 
three volumes of the gas must represent an 
atom and a half. Yet an atom is, by its very 
definition, indivisible. Dr Prout, in the 
38th number of the Annals, restores the true 
proportions of 3 atoms hydrogen -j- 1 azote. 
Our doctrine of equivalent primes, resting on 
the basis of experimental induction, claims 
no knowledge of the atomical constitution of 
bodies. 

The alkaline nature of ammonia is demon- 
strated, not only by its neutralizing acidity, 
and changing the vegetable reds to purple 
or green, but also by its being attracted to 
the negative pole of a voltaic arrangement. 
When a pretty strong electric power is ap- 



AMMONIA. 



151 



AMMONIA. 



plied to ammonia in its liquid or solid com- 
binations, simple decomposition is effected; 
but in contact with mercury, very myste- 
rious phenomena occur. If a globule of 
mercury be surrounded with a little water of 
ammonia, or placed in a little cavity in a 
piece of sal ammoniac, and then subjected to 
the voltaic power by two wires, the negative 
touching the mercury, and the positive the 
ammoniacal compound, the globule is in- 
stantly covered with a circulating film, a 
white smoke rises from it, and its volume 
enlarges, whilst it shoots out ramifications of 
a semi-solid consistence over the salt. The 
amalgam has the consistence of soft butter, 
and may be cut with a knife. Whenever the 
electrization is suspended, the crab-like fibres 
retract towards the central mass, which soon, 
by the constant formation of white saline 
films, resumes its pristine globular shape and 
size. The enlargement of volume seems to 
amount occasionally to ten times that of the 
mercury, when a small globule is employed. 
Sir H. Davy, Berzelius, and MM. Gay Lus- 
sac and Thenard, have studied this singular 
phenomenon with great care. They produc- 
ed the very same substance, by putting an 
amalgam of mercury and potassium into the 
moistened cupel of sal ammoniac. It be- 
comes five or six times larger, assumes the 
consistence of butter, whilst it retains its me- 
tallic lustre. 

What takes place in these experiments? 
In the second case, the substance of metallic 
aspect which we obtain is an ammoniacal 
hydruret of mercury and potassium. There 
is formed, besides, muriate of potash. Con- 
sequently a portion of the potassium of the 
amalgam^ decomposing the water, becomes 
potash, which itself decomposes the muriate 
of ammonia. Thence result hydrogen and 
ammonia, which, in the nascent state, unite 
to the undecomposed amalgam. In the first 
experiment, the substance which, as in the 
second, presents the metallic aspect, is only 
an ammoniacal hydruret of mercury : its for- 
mation is accompanied by the perceptible 
evolution of a certain quantity of chlorine at 
the positive pole. It is obvious, therefore, 
that the salt is decomposed by the electricity. 
The hydrogen of the muriatic acid, and the 
ammonia, both combine with the mercury. 
These hydrurets possess the following pro- 
perties : 

Their sp. gravity is in general below 3.0 : 
exposed for some time to the temperature of 
32 F. they assume considerable hardness, 
and crystallize in cubes, which are often as 
beautiful and large as those of bismuth. 
Ether and alcohol instantly destroy these 
amalgams, exciting a brisk effervescence with 
them, and reproducing the pure mercurial 
globule. These amalgams are slightly per- 
manent in the air, if undisturbed ; but the 
least agitation is fatal to their existence. 



MM. Gay Lussac and Thenard found, by 
immersion in water, that mercury, in passing 
to the state of a hydruret, absorbed 3i- times 
its volume of hydrogen. The ammoniacal 
hydruret of mercury and potassium mav 
exist by itself; but as soon as we attempt to 
separate or oxidize the potassium, its other 
constituent principles also separate. Hence 
this hydruret is speedily decomposed by the 
air, by oxygen gas, and in general by all 
bodies that act upon potassium. It is even 
affected by mercury; so that, in treating it 
with this metal, we may easily determine the 
relative quantity of ammonia and hydrogen 
which it contains. We need only for this 
purpose take up the interior parts of the hy- 
druret with a little iron spoon, fill up with it 
a little glass tube already nearly full of mer- 
cury, and closing this with a very dry stop- 
per, invert it in mercury equally dry. The 
hydruret will rise to the upper part of the 
tube, will be decomposed, especially by a 
slight agitation, and will give out hydrogen 
and ammonia in the ratio of 1 to 2.5. 

The mere ammoniacal hydrurets contain 
but a very small quantity of hydrogen and 
ammonia. By supposing that, in the am- 
moniacal hydruret of mercury, the hydrogen 
is to the ammonia in the same proportion as 
in the ammoniacal hydruret of mercury and 
potassium, it will appear that the first is 
formed, in volume, of 1 of mercury, 3.47 
hydrogen, and 8.67 ammoniacal gas, at the 
mean pressure and temperature of 30, and 
60 ; or in weight, of about 1800 parts of 
mercury, with 1 part of hydrogen, and 1 of 
ammonia. 

M. Hollunder describes a production of 
ammonia, which, in the present state of our 
knowledge, seems equally mysterious as the 
above experimental results. He mixed liver 
of sulphur and pure iron filings together, put 
them into a covered crucible, and exposed 
them to a high temperature. When the 
double sulphuret thus obtained was moisten- 
ed with a little water, it disengaged abun- 
dant vapours of ammonia, and continued to 
do so as long as it remained hot. 

Ammonia is not affected by a> cherry-red 
heat. According to Guyton de Morveau, it 
becomes a liquid at about 40 0, or at 
the freezing point of mercury ; but it is un- 
certain whether the appearances he observed 
may not have been owing to hygrometric 
water, as happens with chlorine gas. The 
ammoniacal liquid loses its pungent smell as 
its temperature sinks, till at 50 it gelati- 
nizes, if suddenly cooled ; but if slowly cool- 
ed, it crystallizes. 

Oxygen, by means of electricity, or a mere 
red heat, resolves ammonia into water and 
nitrogen. When there is a considerable ex- 
cess of oxygen, it acidifies a portion of the 
nitrogen into nitrous acid, whence many falla- 
cies in analvsis have arisen. Chlorine and 



AMMONIA. 



152 



AMMONIA. 



ammonia exercise so powerful an action on 
each other, that when mixed suddenly, a sheet 
of white flame pervades them. The simplest 
way of making this fine experiment, is to in- 
vert a matrass, with a wide mouth and conical 
neck, over another with a taper neck, contain- 
ing a mixture of sal ammoniac and lime, 
heated by a lamp. As soon as the upper ves- 
sel seems to be full of ammonia, by the over- 
flow of the pungent gas, it is to be cautiously 
lifted up, and inserted in a perpendicular di- 
rection into a wide-mouthed glass decanter or 
flask filled with chlorine. On seizing the two 
vessels thus joined with the two hands covered 
with gloves, and suddenly inverting them, like 
a sand-glass, the heavy chlorine and light 
ammonia, rushing in opposite directions, unite 
with the evolution of flame. As one volume 
of ammonia contains, in a condensed state, 
one and a half of hydrogen, which requires 
for its saturation just one and a half of chlo- 
rine, this quantity should resolve the mixture 
into muriatic acid and nitrogen, and thereby 
give a ready analysis of the alkaline gas. If 
the proportion of chlorine be less, sal ammo- 
niac and nitrogen are the results. The same 
thing happens on mixing the aqueous solu- 
tions of ammonia and chlorine. But if large 
bubbles of chlorine be let up in ammoniacal 
water of moderate strength, luminous streaks 
are seen in the dark to pervade the liquid, 
and the same reciprocal change of the ingre- 
dients is effected. 

MM. Gay Lussac and Thenard state, that 
when three parts of ammoniacal gas and one 
of chlorine are mixed together, they condense 
into sal ammoniac, and azote equal to 1-1 Oth 
the whole volume is given out. This result 
is at variance with their own theory of vo- 
lumes. 

Three of ammoniacal gas consist of 4< hy- 
drogen, and 1^ nitrogen in a condensed state : 
1 of chlorine seizes 1 of hydrogen to form 2 
of muriatic acid gas, which precipitate with 2 
of ammonia in a pulverulent muriate. But 
the 3d volume of ammonia had parted with 
1 volume of its hydrogen to the chlorine, and 
another half-volume of hydrogen will unite 
with 0. 166 of a volume of nitrogen, to form 

0.33 of redundant ammonia, while 

0.33 of a volume of nitrogen is left unem- 
ployed. Hence 2-3ds of a volume, or l-6th 
of the original bulk of the mixed gases, ought 
to remain ; consisting of equal parts of am- 
monia and nitrogen, instead of l-10th of 
azote, as the French chemists state. 

Iodine has an analogous action on ammo- 
nia seizing a portion of its hydrogen to form 
hydriodicacid, whence hydriodate of ammonia 
results ; while another portion of iodine unites 
with the liberated nitrogen, to form the ex- 
plosive pulverulent iodide. 

Cyanogen and ammoniacal gas begin to act 
upon each other whenever thev come into con- 



tact, but some hours are requisite to render the 
effect complete. They unite in the propor- 
tion nearly of 1 to 1^, forming a compound 
which gives a dark orange-brown colour to 
water, but dissolves in only a very small quan- 
tity of water. The solution does not produce 
prussian blue with the salts of iron. 

By transmitting ammoniacal gas through 
charcoal ignited in a tube, prussic or hydro- 
cyanic acid is formed. 

The action of the alkaline metals on gase- 
ous ammonia is very curious. When potas- 
sium is fused in that gas, a very fusible olive- 
green substance, consisting of potassium, 
nitrogen, and ammonia, is formed ; and a vo- 
lume of hydrogen remains, exactly equal to 
what would result from the action on water of 
the quantity of potassium employed. Hence, 
according to M. Thenard, the ammonia is 
divided into two portions. One is decom- 
posed, so that its nitrogen combines with the 
potassium, and its hydrogen remains free; 
whilst the other is absorbed in whole or in 
part by the nitroguret of potassium. Sodium 
acts in the same manner. The olive substance 
is opaque, and it is only when in plates of ex- 
treme thinness that it appears semitransparent. 
It has nothing of the metallic appearance; it 
is heavier than water ; and on minute inspec- 
tion seems imperfectly crystallized. When 
it is exposed to a heat progressively increased, 
it melts, disengages ammonia, and hydrogen, 
and nitrogen, in the proportions constituting 
ammonia; then it becomes solid, still pre- 
serving its green colour, and is converted into 
a nitroguret of potassium or sodium. Ex- 
posed to the air at the ordinary temperature, 
it attracts only its humidity but not its oxy- 
gen, and is slowly transformed into ammoni- 
acal gas, and potash or soda. It burns vivid- 
ly when projected into a hot crucible, or when 
heated in a vessel containing oxygen. Water 
and acids produce also sudden decomposition, 
with the extrication of heat. Alkalis or al- 
kaline salts are produced. Alcohol likewise 
decomposes it with similar results. The 
preceding description of the compound of 
ammonia with potassium, as prepared by 
MM. Gay Lussac and Thenard, was contro- 
verted by Sir H. Davy. 

The experiments of this accurate chemist 
led to the conclusion, that the presence of 
moisture had modified their results. In pro- 
portion as more precautions are taken to keep 
every thing absolutely dry, so in proportion 
is less ammonia regenerated. He seldom ob- 
tained as much as 1-1 Oth of the quantity ab- 
sorbed ; and he never could procure hydro- 
gen and nitrogen in the proportions consti- 
tuting ammonia ; there was always an excess 
of nitrogen. The following experiment was 
conducted with the utmost nicety. 3 gr. of 
potassium were heated in 12 cubic inches of 
ammoniacal gas; 7. 5 were absorbed, and 3.2 
of hydrogen evolved. On distilling the olive- 



AMMONIA. 



153 



AMMONIA. 



coloured solid in a tube of platina, 9 cubical 
inches of gas were given off, and half a cu- 
bical inch remained in the tube and adapters. 
Of the 9 cubical inches, l-5th of a cubical 
inch only was ammonia : 10 measures of the 
permanent gas mixed with 7.5 of oxygen, and 
acted upon by the electrical spark, left a re- 
siduum of 7.5. He infers that the results 
of the analysis of ammonia, by electricity and 
potassium, are the same. 

On the whole we may legitimately infer, 
that there is something yet unexplained in 
these phenomena. The potassium separates 
from ammonia as much hydrogen as an equal 
weight of it would from water. If two vo- 
lumes of hydrogen be thus detached from the 
alkaline gas, the remaining volume, with the 
volume of nitrogen, will be left to combine 
with the potassium, forming a triple com- 
pound somewhat analogous to the cyanides, 
a compound capable of condensing ammonia. 
For an account of a singular combination of 
ammonia, by which its volatility seems de- 
stroyed, see CHLORINE. 

When ammoniacal gas is transmitted over 
ignited wires of iron, copper, platina, &c. it 
is decomposed completely, and the several 
metals, when thus treated, become extremely 
brittle. Iron, at the same temperature, de- 
composes the ammonia with double the ra- 
pidity that platinum does. At a high tem- 
perature, the protoxide of nitrogen decom- 
poses ammonia. 

MM. Savartand Despretz have lately shewn, 
that when heated metals are subjected to this 
action of ammoniacal gas, the change of 
weight which they experience is considerable, 
in consequence of combining with some part 
of the ammonia. M. Despretz states, that 
the weight of iron is sometimes increased as 
much as 1 1.5 per cent in such an experiment, 
in consequence of the combination of nitro- 
gen with it. If the temperature applied be 
too high, the nitrogen is expelled, and the 
compound destroyed. 

Copper, iron, and platina, are diminished 
in density, after they have been employed in 
decomposing ammoniacal gas in an ignited 
tube. 

Of the ordinary metals, zinc is the only 
one which liquid ammonia oxidizes and then 
dissolves. But it acts on. many of the me- 
tallic oxides. At a high temperature the gas 
deoxidizes all those which are reducible by 
hydrogen. The oxides soluble in liquid am- 
monia are, the oxide of zinc, the protoxide 
and peroxide of copper, the oxide of silver, 
the third and fourth oxides of antimony, the 
oxide of tellurium, the protoxides of nickel, 
cobalt and iron, the peroxide of tin, mercury, 
gold, and platinum. The first five are very 
soluble, the rest less so. These combinations 
can be obtained by evaporation, in the dry 
state, only with copper, antimony, mercury, 
gold, platinum, and silver; the four last of 



which are very remarkable for. their detonat- 
ing property. See the particular metals. 

All the acids are susceptible of combining 
with ammonia, and they almost all form with 
it neutral compounds. M. Gay Lussac made 
the important discovery, that whenever the 
acid is gaseous, its combination with ammo- 
niacal gas takes place in a simple ratio of de- 
terminate volumes, whether a neutral or a 
subsalt be formed. 

AMMONIACAL SALTS have the fol- 
lowing general characters : 

1st, When treated with a caustic fixed al- 
kali or earth, they exhale the peculiar smell 
of ammonia. 

2d, They are generally soluble in water, 
and crystallizable. 

3d, They are all decomposed at a moderate 
red heat; and if the acid be fixed, as the phos- 
phoric or boracic, the ammonia comes away 
pure. 

4>th, When they are dropped into a solu- 
tion of muriate of platina, a yellow precipi- 
tate falls. 

1. Acetate. This saline compound was 
formerly called the Spirit of Mindererus, who 
introduced it into medicine as a febrifuge 
sudorific. By saturating a pretty strong acetic 
acid with subcarbonate of ammonia, enclosing 
the liquid under the receiver of an air-pump 
along with a saucerful of sulphuric acid, and 
exhausting the air, the salt will concrete in 
acicular crystals, which are nearly neutral. 
It may also be made very conveniently, by 
mixing hot saturated solutions of acetate of 
lead and sulphate of ammonia, taking 100 
of the first salt in its ordinary state to 34.4 
of the second, well dried at a heat of 212. 
Or even muriate of ammonia will answer in 
the proportion of 27.9 to 100 of the acetate. 
Acetate of ammonia has a cooling sweetish 
taste. It is deliquescent, and volatile at all 
temperatures ; but it sublimes in the solid 
state at 250. It consists of 75| of dry acetic 
acid, and 24^ ammonia. When intended for 
medicine, it should always be prepared from 
pure acetic acid and subcarbonate of am- 
monia. 

Arseniate of ammonia may be formed by 
saturating the arsenic acid with ammonia, 
and evaporating the liquid. Crystals of a 
rhomboidal prismatic form are obtained. A 
binarseniate may also be made by using an 
excess of acid. At a red heat, the ammonia 
of both salts is decomposed, and the acid is 
reduced to the metallic state. Under the re- 
spective acids, an account of several ammonia- 
cal salts will be found. As the muriate, how- 
ever, constitutes an extensive manufacture, 
we shall enter here into some additional de- 
tails concerning its production. 

Sal ammoniac was originally fabricated in 
Egypt. The dung of camels and other ani- 
mals constitutes the chief fuel used in that 
country. The soot is carefully collected. 



AMMONIA, 



154 



AMYGDALOID. 



Globular glass vessels, about a foot in dia- 
meter, are filled within a few inches of their 
mouth with it, and are then arranged in an 
oblong furnace, where they are exposed to a 
heat gradually increased. The upper part 
of the glass balloon stands out of the furnace, 
and is kept relatively cool by the air. On 
the third day the operation is completed, at 
which time they plunge an iron rod occasion- 
ally into the mouths of the globes, to prevent 
them from closing up, and thus endanger the 
bursting of the glass. 

The fire is allowed to go out ; and on 
breaking the cooled globes, their upper part 
is found to be lined with sal ammoniac in 
hemispherical lumps, about 2^ inches thick, 
of a greyish-white colour, semitransparent, 
and possessed of a degree of elasticity. 26 
pounds of soot yield 6 of sal ammoniac. The 
ordinary mode of manufacturing sal ammo- 
niac in Europe, is by combining with muri- 
atic acid the ammonia resulting from the 
igneous decomposition of animal matters in 
close vessels. Cylinders of cast-iron, fitted 
up as we have described under ACETIC ACID, 
are charged with bones, horns, parings of hides, 
and other animal matters; and being exposed 
to a full red heat, an immense quantity of an 
impure liquid carbonate of ammonia distils 
over. Mr Minish contrived a cheap method 
of converting this liquid into sal ammoniac. 
He digested it with pulverized gypsum, or 
simply made it percolate through a stratum 
of bruised gypsum ; whence resulted a liquid 
sulphate of ammonia, and an insoluble car- 
bonate of lime. The liquid, evaporated to 
dryness, was mixed with muriate of soda, 
put into large glass balloons, and decomposed 
by a subliming heat. Sal ammoniac was 
found above in its characteristic cake, while 
sulphate of soda remained below. 

M. Leblanc of St Denis, near Paris, in- 
vented another method of much ingenuity, 
which is described by a commission of emi- 
nent French chemists in the 19th volume of 
the Annales de Chimie, and in the Journal 
de Physique for the year 1794. He used 
tight brick kilns, instead of iron cylinders, 
for holding the materials to be decomposed. 
Into one he put a mixture of common salt 
and oil of vitriol ; into another, animal mat- 
ters. Heat extricated from the first muriatic 
acid gas, and from the second ammonia ; 
which bodies being conducted by their re- 
spective flues into a third chamber lined with 
lead, and containing a stratum of water on 
its bottom, entered into combination, and 
precipitated in solid sal ammoniac on the roof 
and sides, or in liquid at the bottom. 

In the 20th volume of the Annales, a plan 
for employing bittern or muriate of magnesia 
to furnish the acid ingredient is described. 
An ingenious process on the same principles 
was some time ago commenced at Borrow- 
stounness in Scotland, by Mr Astley. He 



imbued in a stove-room, heated by brick flues, 
parings of skins, horns, and other animal 
matters, with the muriate of magnesia, or 
mother water of the sea-salt works. The 
matters thus impregnated and dried were 
subjected in a close kiln to a red heat, when 
the sal ammoniac vapour sublimed, and was 
condensed either in a solid form into an 
adjoining chamber or chimney, or else into a 
stratum of water on its bottom. Muriate of 
magnesia at a red heat evolves muriatic acid 
gas ; an evolution probably aided in the pre- 
sent case by the affinity of ammonia. 

From coal soot likewise a considerable 
quantity of ammonia, in the state of carbo- 
nate and sulphate, may be obtained, either by 
sublimation or lixiviation with water. These 
ammoniacal products can afterwards be readily 
converted into the muriate, as above describ- 
ed". M. Leblanc used a kettle or eolipile 
for projecting steam into the leaden chamber, 
to promote the combination. It is evident, 
that the exact neutralization essential to sal 
ammoniac might not be hit at first in these 
operations ; but it could be afterwards effect- 
ed by the separate addition of a portion of 
alkaline or acid gas. As the mother waters 
of the Cheshire salt works contain only 3 
per cent of muriate of magnesia, they are not 
suitable, like those of sea-salt works, for the 
above manufacture. See SALT. 

AMMONIAC (GUM). This is a gum 
resin, which consists, according to Bracon- 
not, of 70 resin, 18.4 gum, 4.4 glutinous 
matter, 6 water, and 1.2 loss, in 100 parts. 
It forms a milky solution with water; is par- 
tially soluble in alcohol ; entirely in ether, 
nitric acid, and alkalis. Sp. gr. 1.200. It 
has rather a heavy smell, and a bitter-sweet 
taste. It is in small agglutinated pieces of 
a yellowish-white colour. It is used in me- 
dicine as an expectorant and antispasmodic. 

AMMONITES. These petrifactions, 
which have likewise been distinguished by 
the name of cornua ammonis, and are called 
snake-stones by the vulgar, consist chiefly of 
lime-stone. They are found of all sizes, 
from the breadth of half an inch to more 
than two feet in diameter ; some of them 
rounded, others greatly compressed, and 
lodged in different strata of stones and clays. 
They appear to owe their origin to shells of 
the nautilus kind. 

AMOMUM. See PIMENTO. 

AMPELITE. The aluminous ampelite 
is the alum slate, and the graphic, the gra- 
phic slate. 

AMPHIBOLE. See HORNBLENDE, and 

ACTYNOLITE. 

AMPHIBOLITES. In geology, trap 
rocks, the basis of which is amphibole or 
hornblende. 

AM PHI GENE. See VESUVIAN. 

AMYGDALOID. A compound mi- 
neral, consisting of spheroidal particles or 



ANALYSIS. 



155 



ANALYSIS. 



vesicles of lithomarge, green earth, calc spar, 
steatite, imbedded in a basis of fine-grained 
greenstone, or wacke, containing sometimes 
also crystals of hornblende. 

AMYLINE or AMYDINE. Saussure 
exposed a solution of starch in twelve times 
its weight of water to the air, in a shallow 
capsule, for two years. It had then become 
a grey liquid, covered with mould, free from 
smell, and without action on vegetable blue 
colours. The starch had lost nearly one- 
fourth of its weight, and the remainder was 
converted into the following substances : 1. 
Sugar, amounting to one-half of the starch ; 
2. Gum, or a substance analogous to it, ob- 
tained by roasting starch ; 3. Amyline ; 4. 
Starchy lignine ; 5. Lignine mixed with char- 
coal. Amyline is intermediate between gum 
and starch. It is soluble in boiling water, 
and the solution affords by evaporation a pale 
semitransparent brittle substance, insoluble 
in alcohol, but soluble in ten times its weight 
of cold water, and to any extent in water at 
144. The solution becomes a white paste 
with subacetate of lead. With iodine it be- 
comes blue. It is precipitated by baryta 
water, but not by lime water, potash, soda, 
or galls. Phil. Trans. 1819. 

ANACARDIUM, cashew nut, or mark- 
ing nut. At one extremity of the fruit of 
the cashew tree is a flattish kidney-shaped 
nut, between the rind of which and the thin 
outer shell is a small quantity of a red, thick- 
ish, inflammable, and very caustic liquor. 
This liquor forms an useful marking ink, as 
any thing written on linen or cotton with it 
is of a brown colour, which gradually grows 
blacker, and is very durable. 

ANALCIME. Cubic zeolite. This mi- 
neral is generally found in aggregated or 
cubic crystals, whose solid angles are replaced 
by three planes. External lustre between 
vitreous and pearly ; fracture flat conchoidal ; 
colours, white, grey, or reddish ; translucent. 
From the becoming feebly electrical by heat 
it has got the name analcime. Its sp. gr. is 
less than 2.6. It consists of 58 silica, 18 
alumina, 2 lime, 10 soda, 8 water, and 3 
loss, in 100 parts. It is found in granite", 
gneiss, trap rocks and lavas, at Calton Hill 
Edinburgh, at Talisker in Sky, in Dumbar- 
tonshire, in the Hartz, Bohemia, and at the 
Ferroe Islands. The variety found at Som- 
ma has been called sarcolite> from its flesh 
colour. 

ANALYSIS. Chemical analysis consists 
of a great variety of operations, performed 
for the purpose of separating the component 
parts of bodies. In these operations the 
most extensive knowledge of such properties 
of bodies as are already discovered must be 
applied, in order to produce simplicity of 
effect, and certainty in the results. Chemi- 
cal analysis cannot be executed with success 
by one who is not in possession of a consider- 



able number of simple substances in a state 
of great purity, which, from their effects, are 
called reagents. The word analysis is applied 
by chemists to denote that series of operations 
by which the component parts of bodies are 
determined, whether they be merely separa- 
ted, or exhibited apart from each other ; or 
whether these distinctive properties be ex- 
hibited by causing them to enter into new 
combinations. The forming of new combi- 
nations is called synthesis ; and, in the chemi- 
cal examination of bodies, analysis or separa- 
tion can scarcely ever be effected, without 
synthesis taking place at the same time. 

As most of the improvements in the science 
of chemistry consist in bringing the art of 
analysis nearer to perfection, it is not easy to 
give any other rule to the learner, than the 
general one of consulting and remarking the 
processes of the best chemists, such as Scheele, 
Bergman, Klaproth, Kirwan, Vauquelin, and 
Berzelius. The bodies which present them- 
selves more frequently for examination than 
others are, minerals, and mineral waters. In 
the examination of the former, it was the 
habit of the earlier chemists to avail them- 
selves of the action of fire, with very few 
humid processes, which are such as might be 
performed in the usual temperature of the 
atmosphere. Modern chemists have improv- 
ed the process by fire, by a very extensive use 
of the blowpipe, (see BLOWPIPE) ; and have 
succeeded in determining the component parts 
of minerals to great accuracy in the humid 
way. For the method of analyzing mineral 
waters, see WATERS (MINERAL); and for 
the analysis of metallic ores, see ORES. 

Several authors have written on the ex- 
amination of earths and stones. 

The first step in the examination of indu- 
rated earths or stones, is somewhat different 
from that of such as are pulverulent. Their 
specific gravity should first be examined ; also 
their hardness, whether they will strike fire 
with steel, or can be scratched by the nail, 
or only by crystal, or stones of still greater 
hardness ; also their texture, perviousness to 
light, and whether they be manifestly homo- 
geneous or compound species, c. 

2d, In some cases, we should try whether 
they imbibe water, or whether water can ex- 
tract any thing from them by ebullition or 
digestion. 

3d, Whether they be soluble in, or effer- 
vesce with acids, before or after pulverization ; 
or whether decomposable by boiling in a 
strong solution of potash, &c., as gypsums 
and ponderous spars are. 

4>th, Whether they detonate with nitre. 

5th, Whether they yield the fluoric acid by 
distillation with sulphuric acid or ammonia, 
by distilling them with potash. 

6th, Whether they be fusible per se with 
a blowpipe, and how they are affected by soda, 



ANALYSIS. 



156 



ANALYSIS. 



borax, and microcosmic salt ; and whether 
they decrepitate when gradually heated. 

It h, Stones that melt per se with the blow- 
pipe are certainly compound, and contain at 
least three species of earth, of which the cal- 
careous is probably one ; and if they give fire 
with steel, the siliceous is probably another. 

The general process prescribed by the 
celebrated Vauquelin, in the 30th volume of 
the Annales de Chimie, is the clearest which 
has yet been offered to the chemical student. 

If the mineral be very hard, it is to be 
ignited in a covered crucible of platinum, and 
then plunged into cold water, to render it 
brittle and easily pulverizable. The weight 
should be noted before and after this opera- 
tion, in order to see if any volatile matter has 
been emitted. For the purpose of reducing 
stones to an impalpable powder, little mortars 
of highly hardened steel are now made, con- 
sisting of a cylindrical case and pestle. A 
mortar of agate is also used for subsequent 
levigation. About ten grains of the mineral 
should be treated at once ; and after the whole 
100 grains have been reduced in succession 
to an impalpable powder, they should be 
weighed, to find what increase may have been 
derived from the substance of the agate. 
This addition may be regarded as silica. 

Of the primary earths, only four are usually 
met with in minerals, viz. silica, alumina, 
magnesia, and lime, associated with some me- 
tallic oxides, which are commonly iron, man- 
ganese, nickel, copper, and chromium. 

If neither acid nor alkali be expected to be 
present, the mineral is mixed in a silver cru- 
cible, with thrice its weight of pure potash 
and a little water. Heat is gradually applied 
to the covered crucible, and is finally raised 
to redness ; at which temperature it ought to 
be maintained for an hour. If the mass, on 
inspection, be a perfect glass, silica may be re- 
garded as the chief constituent of the stone ; 
but if the vitrification be very imperfect, and 
the bulk much increased, alumina may be 
supposed to predominate. A brownish or 
dull green colour indicates the presence of 
iron ; a bright grass-green, which is imparted 
to water, that of manganese; and from a 
greenish-yellow, chromium may be expected. 
The crucible, still a little hot, being first 
wiped, is put into a capsule of porcelain or 
platinum ; when warm distilled water is 
poured upon the alkaline earthy mass, to de- 
tach it from the crucible. Having transferred 
the whole of it into the capsule, muriatic acid 
is poured on, and a gentle heat applied, if 
necessary, to accomplish its solution. If the 
liquid be of an orange-red colour, we infer 
the presence of iron ; if of agolden yellow, that 
of chromium ; and if of a purplish-red, that of 
manganese. The solution is next to be eva- 
porated to dry ness on a sand bath, or over a 
lamp, taking care so to regulate the heat that 
no particles be thrown out. Towards the 



end of the evaporation, it assumes a gelatinous 
consistence. At this period it must be stirred 
frequently with a platinum spatula or glass 
rod, to promote the disengagement of the 
muriatic acid gas. After this, the heat may 
be raised to fully 212 F. for a few minutes. 
Hot water is now to be poured on in consi- 
derable abundance, which dissolves every 
thing except the silica. By filtration, this 
earth is separated from the liquid ; and being 
edulcorated with hot water, it is then dried, 
ignited, and weighed. It constitutes a fine 
white powder, insoluble in acids, and feeling 
gritty between the teeth. If it be coloured, 
a little dilute muriatic acid must be digested 
on it, to remove the adhering metallic par- 
ticles, which must be added to the first solu- 
tion. This must now be reduced by evapo- 
ration to the bulk of half a pint. Carbonate 
of potash being then added till it indicates 
alkaline excess, the liquid must be made to 
boil for a little. A copious precipitation of 
the earth and oxides is thus produced. The 
whole is thrown on a filter, and after it is so 
drained as to assume a semi-solid consistence, 
it is removed by a platinum blade, and boiled 
in a capsule for some time with solution of 
pure potash. Alumina and glucina are thus 
dissolved, while the other earths and the me- 
tallic oxides remain. 

This alkalino-earthy solution, separated 
from the rest by filtration, is to be treated 
with an excess of muriatic acid ; after which 
carbonate of ammonia being added also in 
excess, the alumina is thrown down, while the 
glucina continues dissolved. The first earth 
separated by filtration, washed, dried, and 
ignited, gives the quantity of alumina. The 
nature of this may be further demonstrated 
by treating it with dilute sulphuric acid and 
sulphate of potash, both in equivalent quan- 
tities, when the whole will be converted into 
alum. (See ALUM.) The filtered liquid will 
deposit its glucina, on dissipating the am- 
monia by ebullition. It is to be separated 
by filtration, to be washed, ignited, and 
weighed. 

The matter undissolved by the digestion of 
the liquid potash, may consist of lime, mag- 
nesia, and metallic oxides. Dilute sulphuric 
acid must be digested on it for some time. 
The solution is to be evaporated to dryness, 
and heated, to expel the excess of acid. The 
saline solid matter being now diffused in a 
moderate quantity of water, the sulphate of 
magnesia will be dissolved, and, along with 
the metallic sulphates, may be separated from 
the sulphate of lime by the filter. The latter 
being washed with a little water, dried, ig- 
nited, and weighed, gives, by the scale of 
equivalents, the quantity of lime in the mine- 
ral. The magnesian and metallic solution 
being diluted with a large quantity of water, 
is to be treated with bicarbonate of potash, 
which will precipitate the nickel, iron, and 



ANALYSIS. 



157 



ANALYSIS. 



chromium, but retain the magnesia and man- 
ganese, by the excess of carbonic acid. Hy- 
drosulphuret of potash will throw down the 
manganese from the magnesian solution. 
The addition of pure potash, aided by gentle 
ebullition, will then precipitate the magnesia. 
The oxide of manganese may be freed from 
the sulphuretted hydrogen by ustulation. 

The mingled metallic oxides must be di- 
gested with abundance of nitric acid, to aci- 
dify the chromium. The liquid is next treated 
with potash, which forms a soluble chromate, 
while it throws down the iron and nickel. 
The chromic acid may be separated from the 
potash by muriatic acid and digestion with 
heat, washed, dried till it become a green 
oxide, and weighed. The nickel is separated 
from the iron, by treating their solution in 
muriatic acid with water of ammonia. The 
latter oxide, which falls, may be separated by 
the filter, dried and weighed. By evaporat- 
ing the liquid, and exposing the dry residue 
to a moderate heat, the ammoniacal salt will 
sublime, and leave the oxide of nickel behind. 
The whole separate weights must now be col- 
lected in one amount, and if they constitute 
a sum within two per cent of the primitive 
weight, the analysis may be regarded as giving 
a satisfactory account of the composition of 
the mineral. But if the deficiency be con- 
siderable, then some volatile ingredient, or 
some alkali or alkaline salt, may be suspected. 

A portion of the mineral, broken into small 
fragments, is to be ignited in a porcelain re- 
tort, to which a refrigerated receiver is fitted. 
The water, or other volatile and condensable 
matter, if any be present, will thus be ob- 
tained. But if no loss of weight be sustained 
by ignition, alkali, or a volatile acid, may be 
looked for. The latter is usually the fluoric. 
It may be expelled by digestion with sulphu- 
ric acid. It is exactly characterized by its 
property of corroding glass. 

Beside this general method, some others 
may be used in particular cases. 

Thus, to discover a small proportion of 
alumina or magnesia in a solution of a large 
quantity of lime, pure ammonia may be ap- 
plied, which will precipitate the alumina or 
magnesia, (if any be), but not the lime. Dis- 
tilled vinegar applied to the precipitate will 
discover whether it be alumina or magnesia. 

2dly, A minute portion of lime or baryta, 
in a solution of alumina or magnesia, may 
be discovered by the sulphuric acid, which 
precipitates the lime and baryta : the solution 
should be dilute, else the alumina also would 
be precipitated. If there be not an excess of 
acid, the oxalic acid is still a nicer test of lime : 
100 grains of gypsum contain about 33 of 
lime; 100 grains of sulphate of baryta con- 
tain 66 of baryta; 100 grains of oxalate of 
lime contain 43.8 of lime. The insolubility 
of sulphate of baryta in 500 times its weight 
of boiling water, sufficiently distinguishes it. 



From these data the quantities are easily in- 
vestigated. 

3dly, A minute proportion of alumina in 
a large quantity of magnesia may be dis- 
covered, either by precipitating the whole, 
and treating it with distilled vinegar ; or by 
heating the solution nearly to ebullition, and 
adding more carbonate of magnesia until the 
solution is perfectly neutral, which it never is 
when alumina is contained in it, as this re- 
quires an excess of acid to keep it in solution. 
By these means the alumina is precipitated in 
the state of embryon alum, which contains 
about half its weight of alumina; (or, for 
greater exactness, it may be decomposed by 
boiling it in volatile alkali). After the pre- 
cipitation the solution should be largely di- 
luted, as the sulphate of magnesia, which re- 
mained in solution while hot, would precipi- 
tate when cold, and mix with the embryon 
alum. 

fahly, A minute portion of magnesia in a 
large quantity of alumina is best separated by 
precipitating the whole, and treating the pre- 
cipitate with distilled vinegar. 

Lastly, Lime and baryta are separated by 
precipitating both with the sulphuric acid, 
and evaporating the solution to a small com- 
pass, pouring off the liquor, and treating the 
dried precipitate with 500 times its weight of 
boiling water : what remains undissolved is 
sulphate of baryta. 

The inconveniencies of employing much 
heat are obvious, and M. Lowitz informs us 
that they may be avoided without the least 
disadvantage. Over the flame of a spirit 
lamp, that will hold an ounce and a half, and 
is placed in a cylindrical tin furnace, four 
inches high and three in diameter, with air- 
holes, and a cover perforated to hold the cru- 
cible, he boils the stone prepared as directed 
above, stirring it frequently. His crucible, 
which, as well as the spatula, is of very fine 
silver, holds two ounces and a half, or three 
ounces. As soon as the matter is boiled dry, 
he pours in as much hot water as he used at 
first ; and this he repeats two or three times 
more, if the refractoriness of the fossil require 
it. Large tough bubbles arising during the 
boiling, are in general a sign that the process 
will be attended with success. .Even the 
sapphire, though the most refractory of all 
M. Lowitz tried, was not more so in this 
than in the dry way. 

Sir H. Davy observes, that boracic acid is 
very useful in analyzing stones that contain a 
fixed alkali ; as its attraction for the different 
earths at the heat of ignition is considerable, 
and the compounds it forms with them are 
easily decomposed by the mineral acids dis- 
solved in water. His process is as follows : 
Let 100 grains of the stone to be examined 
be reduced to a fine powder, mixed with 200 
grains of boracic acid, and fused for about 
half an hour at a strong red heat in a crucible 



ANALYSIS. 



158 



ANALYSIS. 



of platina or silver. Digest the fused mass in 
an ounce and half of nitric acid, diluted with 
seven or eight times the quantity of water, 
till the whole is decomposed ; and then eva- 
porate the solution till it is reduced to an 
ounce and half, or two ounces. If the stone 
contained silex, it will separate in this process, 
and must be collected on a filter, and edulco- 
rated with distilled water to separate the sa- 
line matter. The fluid, mixed with all the 
water that has been passed through the filter, 
being evaporated till reduced to about half a 
pint, is to be saturated with carbonate of am- 
monia, and boiled with an excess of this salt, 
till all that will precipitate has fallen down. 
The earths and metallic oxides being sepa- 
rated by filtration, mix nitric acid with the 
clear fluid till it has a strongly sour taste, and 
then evaporate till the boracic acid remains 
free. Filter the fluid, evaporate it to dryness, 
and expose it to a heat of 450 F., when the 
nitrate of ammonia will be decomposed, and 
the nitrate of potash or soda will remain in the 
vessel. The earths and metallic oxides that 
remained on the filter, may be distinguished 
by the common processes. The alumina may 
be separated by solution of potash, the lime by 
sulphuric acid, the oxide of iron by succinate 
of ammonia, the manganese by hydrosulphu- 
ret of potash, and the magnesia by pure soda. 
Lately, carbonate or nitrate of baryta, and 
carbonate with nitrate of lead, have been in- 
troduced into mineral analysis with great ad- 
vantage, for the fluxing of stones that may 
contain alkaline matter. See Mr Children's 
Translation of M. Thenard's volume on Ana- 
lysis. 

M. Berthier shews, that the ready fusion 
of certain atomic mixtures of salts, may be 
applied to the analysis of siliceous minerals 
by alkaline carbonates, aided by a spirit lamp. 
A mixture of five parts of carbonate of pot- 
assa, and four parts of carbonate of soda, is 
so fusible, that between 200 and 300 grains 
may be rendered perfectly liquid by a spirit 
flame. If sand be added to the mixture, 
there is an effervescence as lively as if acid 
had been added. The operation should, 
therefore, commence with the mixture of the 
carbonates and the mineral. In this manner, 
insoluble quantities of felspar may be readily 
decomposed by the heat of a spirit of wine 
lamp. 

M. Berzelius has very recently employed 
fluoric acid in a most ingenious manner for 
the analysis of siliceous minerals. In ex- 
tracting lithia, for example, from triphane or 
spodumene, he mixes the mineral, in powder, 
with twice its weight of pulverized fluor-spar, 
and with sulphuric acid ; he then heats the 
mixture so that the fluoric acid shall carry off 
the silica in the form of fluosilicic acid gas, 
and he afterwards separates the sulphate of 
lithia from the residuary matter by solution. 
Under the head of mineral analysis, nothing 



is of so much general importance as the exa- 
mination of soils, with a view to the improve- 
ment of such as are less productive, by sup- 
plying the ingredients they want in due 
proportions to increase their fertility. To 
Lord Dundonald and Mr Kirwan we are 
much indebted for their labours in this field 
of inquiry ; but Sir H. Davy, assisted by the 
labours of these gentlemen, the facts and ob- 
servations of Mr Young, and his own skill 
in chemistry, having given at large, in a 
manner best adapted for the use of the prac- 
tical farmer, an account of the methods to be 
pursued for this purpose, we shall here copy 
them. 

The substances found in soils are certain 
mixtures or combinations of some of the pri- 
mitive earths, animal and vegetable matter in 
a decomposing state, certain saline compounds, 
and the oxide of iron. These bodies always 
retain water, and exist in very different pro- 
portions in different lands ; and the end of 
analytical experiments is the detection of 
their quantities and mode of union. 

The earths commonly found in soils are 
principally silex, or the earth of flints ; alu- 
mina, or the pure matter of clay ; lime, or 
calcareous earth ; and magnesia : for the cha- 
racters of which see the articles. Silex com- 
poses a considerable part of hard gravelly 
soils, hard sandy soils, and hard stony lands. 
Alumina abounds most in clayey soils, and 
clayey loams ; but even in the smallest par- 
ticles of these soils it is generally united with 
silex and oxide of iron. Lime always exists 
in soils in a state of combination, and chiefly 
with carbonic acid, when it is called carbonate 
of lime. This carbonate in its hardest state 
is marble ; in its softest, chalk. Lime united 
with sulphuric acid is sulphate of lime, or 
gypsum ; with phosphoric acid, phosphate of 
lime, or the earth of bones. Carbonate of 
lime, mixed with other substances, composes 
chalky soils and marls, and is found in soft 
sandy soils. Magnesia is rarely found in 
soils ; when it is, it is combined with carbonic 
acid, or with silex and alumina. Animal 
decomposing matter exists in different states, 
contains much carbonaceous substance, vo- 
latile alkali, inflammable aeriform products, 
and carbonic acid. It is found chiefly in 
lands lately manured. Vegetable decom- 
posing matter usually contains still more car- 
bonaceous substance, and differs from the 
preceding, principally, in not producing vo- 
latile alkali. It forms a great proportion of 
all peats, abounds in rich mould, and is found 
in larger or smaller quantities in all lands. 
The saline compounds are few, and in small 
quantity ; they are chiefly muriate of soda, 
or common salt, sulphate of magnesia, mu- 
riate and sulphate of potash, nitrate of lime, 
and the mild alkalis. Oxide of iron, which 
is the same with the rust produced by ex- 
posing iron to air and water, is found in all 



ANALYSIS. 



159 



ANALYSIS. 



soils, but most abundantly in red and yellow 
clays, and red and yellow siliceous sands. 

The instruments requisite for the analysis 
of soils are few. A pair of scales capable of 
holding a quarter of a pound of common soil, 
and turning with a single grain when loaded : 
a set of weights, from a quarter of a pound 
troy to a grain : a wire sieve, coarse enough to 
let a pepper-corn pass through : an Argand 
lamp and stand : a few glass bottles, Hessian 
crucibles, and china or queen's ware evapo- 
rating basins : a Wedgwood pestle and mor- 
tar : some filters made of half a sheet of 
blotting paper, folded so as to contain a pint 
of liquid, and greased at the edges : a bone 
knife ; and an apparatus for collecting and 
measuring aeriform fluids. 

The reagents necessary are muriatic acid, 
sulphuric acid, pure volatile alkali dissolved 
in water, solution of prussiate of potash, 
soap lye, and solutions of carbonate of am- 
monia, muriate of ammonia, neutral carbo- 
nate of potash, and nitrate of ammonia. 

1. When the general nature of the soil of 
a field is to be ascertained, specimens of it 
should be taken from different places, two 
or three inches below the surface, and exa- 
mined as to the similarity of their properties. 
It sometimes happens, that on plains the 
whole of the upper stratum of the land is of 
the same kind, and in this case one analysis 
will be sufficient. But in valleys, and near 
the beds of rivers, there are very great differ- 
ences, and it now and then occurs, that one 
part of a field is calcareous, and another part 
siliceous ; and in this and analogous cases, 
the portions different from each other should 
be analyzed separately. Soils when collect- 
ed, if they cannot be examined immediately, 
should be preserved in phials quite filled with 
them, and closed with ground glass stopples. 
The most convenient quantity for a perfect 
analysis is from two hundred grains to four 
hundred. It should be collected in dry wea- 
ther, and exposed to the air till it feels dry. 
Its specific gravity may be ascertained, by 
introducing into a phial, which will contain a 
known quantity of water, equal bulks of water 
and of the soil ; which may easily be done 
by pouring in water till the phial is half full, 
and then adding the soil till the fluid rises 
to the mouth. The difference between the 
weight of the water and that of the soil will 
give the result. Thus, if the bottle will con- 
tain four hundred grains of water, and gains 
two hundred grains when half filled with 
water and half with soil, the specific gravity 
of the soil will be 2 ; that is, it will be twice 
as heavy as water : and if it gained one hun- 
dred and sixty-five grains, its specific gravity 
would be 1825, water being 1000. It is o"f 
importance that the specific gravity of a soil 
should be known, as it affords an indication 
of the quantity of animal and vegetable mat- 
ter it contains; these substances being always 



most abundant in the lighter soils. The 
other physical properties of soils should like- 
wise be examined before the analysis is made, 
as they denote, to a certain extent, their com- 
position, and serve as guides in directing the 
experiments. Thus, siliceous soils are gene- 
rally rough to the touch, and scratch glass 
when rubbed upon it ; aluminous soils ad- 
here strongly to the tongue, and emit a 
strong earthy smell when breathed upon ; 
and calcareous soils are soft, and much less 
adhesive than aluminous soils. 

2. Soils, when as dry as they can be made 
by exposure to the air, still retain a consider- 
able quantity of water, which adheres with 
great obstinacy to them, and cannot be driven 
off without considerable heat : and the first 
process of analysis is to free them from as 
much of this water as possible, without affect- 
ing their composition in other respects. This 
may be done by heating the soil for ten or 
twelve minutes in a china basin over an 
Argand lamp, at a temperature equal to 
300 F. ; and if a thermometer be not used, 
the proper degree of heat may easily be ascer- 
tained by keeping a piece of wood in the basin 
in contact with its bottom ; for as long as the 
colour of the wood remains unaltered, the heat 
is not too high ; but as soon as it begins to be 
charred, the process must be stopped. In 
several experiments, in which Sir H. Davy 
collected the water that came over at this 
degree of heat, he found it pure, without any 
sensible quantity of other volatile matter 
being produced. The loss of weight in this 
process must be carefully noted ; and if it 
amount to 50 grains in 400 of the soil, this 
may be considered as in the greatest degree 
absorbent and retentive of water, and will 
generally be found to contain a large pro- 
portion of aluminous earth. If the loss be 
not more than 10 or 20 grains, the land may 
be considered as slightly absorbent and re- 
tentive, and the siliceous earth as most abun- 
dant. 

3. None of the loose stones, gravel, or 
large vegetable fibres, should be separated 
from the soil till the water is thus expelled ; 
for these bodies are often highly absorbent 
and retentive, and consequently influence the 
fertility of the land. But after the soil has 
been heated as above, these should be sepa- 
rated by the sieve, after the soil has been 
gently bruised in a mortar. The weights of 
the vegetable fibres or wood, and of the 
gravel and stones, should be separately noted 
down, and the nature of the latter ascertain- 
ed : if they be calcareous, they will effervesce 
with acids ; if siliceous, they will scratch 
glass ; if aluminous, they will be soft, easily 
scratched with a knife, and incapable of ef- 
fervescing with acids. 

4. Most soils, besides stones and gravel, 
contain larger or smaller proportions of sand 
of different degrees of fineness ; and the next 



ANALYSIS. 



ICO 



ANALYSIS. 



operation necessary is to separate this sand 
from the parts more minutely divided, such 
as clay, loam, marl, and vegetable and animal 
matter. This may be done sufficiently by 
mixing the soil well with water; as the coarse 
sand will generally fall to the bottom in the 
space of a minute, and the finer in two or 
three : so that by pouring the water off' after 
one, two, or three minutes, the sand will be 
for the most part separated from the other 
substances ; which, with the water containing 
them, must be poured into a filter. After 
the water has passed through, what remains 
on the filter must be dried and weighed, as 
must also the sand; and their respective 
quantities must be noted down. The water 
must be preserved, as it will contain the saline 
matter, and the soluble animal or vegetable 
matter, if any existed in the soil. 

5. A minute analysis of the sand thus se- 
parated is seldom or never necessary, and its 
nature may be detected in the same way as 
that of the stones and gravel. It is always 
siliceous sand, or calcareous sand, or both 
together. If it consist wholly of carbonate 
of lime, it will dissolve rapidly in muriatic 
acid with effervescence; but if it consist 
partly of this and partly of siliceous matter, 
a residuum will be left after the acid has 
ceased to act on it, the acid being added till 
the mixture has a sour taste, and has ceased 
to effervesce. This residuum is the siliceous 
part ; which being washed, dried, and heated 
strongly in a crucible, the difference of its 
weight from that of the whole will indicate 
the quantity of the calcareous sand. 

6. The finely divided matter of the soil is 
usually very compound in its nature: it 
sometimes contains all the four primitive 
earths of soils, as well as animal and vege- 
table matter ; and to ascertain the proportions 
of these with tolerable accuracy, is the most 
difficult part of the subject. The first pro- 
cess to be performed in this part of the ana- 
lysis, is the exposure of the fine matter of the 
soil to the action of muriatic acid. This 
acid, diluted with double its bulk of water, 
should be poured upon the earthy matter in 
an evaporating basin, in a quantity equal to 
twice the weight of the earthy matter. The 
mixture should be often stirred, and suffered 
to remain for an hour, or an hour and a half, 
before it is examined. If any carbonate of 
lime, or of magnesia, exist in the soil, they 
will have been dissolved in this time by the 
acid, which sometimes takes up likewise a 
little oxide of iron, but very seldom any 
alumina. The fluid should be passed through 
a filter; the solid matter collected, washed 
with distilled or rain water, dried at a mode- 
rate heat, and weighed. Its loss will denote 
the quantity of solid matter taken up. The 
washings must be added to the solution ; 
which, if not sour to the taste, must be made 
so by the addition of fresh acid ; and a little 



solution of prussiate of potash must be mixed 
with the liquor. If a blue precipitate occur, 
it denotes the presence of oxide of iron ; and 
the solution of the prussiate must be dropped 
in, till no further effect is produced. To 
ascertain its quantity, it must be collected on 
a filter in the same manner as the other solid 
precipitates, and heated red : the result will 
be oxide of iron. Into the fluid freed from 
oxide of iron, a solution of carbonate of 
potash must be poured, till all effervescence 
ceases in it, and till its taste and smell indi- 
cate a considerable excess of alkaline salt. 
The precipitate that falls down is carbonate 
of lime, which must be collected on a filter, 
dried at a heat below that of redness, and 
afterwards weighed. The remaining fluid 
must be boiled for a quarter of an hour, when 
the magnesia, if there be any, will be pre- 
cipitated combined with carbonic acid ; and 
its quantity must be ascertained in the same 
manner as that of the carbonate of lime. If 
any minute proportion of alumina should, 
from peculiar circumstances, be dissolved by 
the acid, it will be found in the precipitate 
with the carbonate of lime, and it may be 
separated from it by boiling for a few minutes 
with soap lye sufficient to cover the solid 
matter : for this lye dissolves alumina, with- 
out acting upon carbonate of lime. Should 
the finely divided soil be sufficiently calcare- 
ous to effervesce very strongly with acids, a 
simple method of ascertaining the quantity 
of carbonate of lime, sufficiently accurate in 
all common cases, may be adopted. As car- 
bonate of lime in all its states contains a de- 
terminate quantity of acid, which is about 
44 parts in a hundred by weight, the quanti- 
ty of this acid given out during the efferves- 
cence occasioned by its solution in a stronger 
acid, will indicate the quantity of carbonate 
of lime present. Thus, if you weigh sepa- 
rately one part of the matter of the soil, and 
two parts of the acid diluted with an equal 
quantity of water, and mix the acid slowly in 
small portions with the soil, till it ceases to 
occasion any effervescence, by weighing the 
mixture, and the acid that remains, you will 
find the quantity of carbonic acid lost; and 
for every four grains and half so lost, you 
will estimate ten grains of carbonate of lime. 
You may also collect the carbonic acid in the 
pneumatic apparatus for the analysis of soils, 
described in the article LABORATORY; and 
allow for every ounce measure of the carbonic 
acid, two grains of carbonate of lime. 

7. The quantity of insoluble animal and 
vegetable matter may next be ascertained 
with sufficient precision, by heating it to a 
strong red heat in a crucible over a common 
fire till no blackness remains in the mass, 
stirring it frequently meanwhile with a me- 
tallic wire. The loss of weight will ascertain 
the quantity of animal and vegetable matter 
there was, but not the proportions of each. If 



ANALYSIS. 



161 



ANALYSIS. 



the smell emitted, during this process, resem- 
ble that of burnt feathers, it is a certain indi- 
cation of the presence of some animal matter ; 
and a copious blue flame almost always de- 
notes a considerable proportion of vegetable 
matter. Nitrate of ammonia, in the propor- 
tion of twenty grains to a hundred of the re- 
siduum of the soil, will greatly accelerate this 
process, if the operator be in haste ; and not 
affect the result, as it will be decomposed and 
evaporate. 

8. What remains after this decomposition 
of the vegetable and animal matter, consists 
generally of minute particles of earthy mat- 
ter, which are usually a mixture of alumina 
and silex with oxide of iron. To separate 
these, boil them two or three hours in sul- 
phuric acid diluted with four times its weight 
of water, allowing a hundred and twenty 
grains of acid for every hundred grains of 
the residuum. 

If any thing remain undissolved by this 
acid, it may be considered as silex, and be 
separated, washed, dried, and weighed in the 
usual manner. Carbonate of ammonia being 
added to the solution, in quantity more than 
sufficient to saturate the acid, the alumina 
will be precipitated ; and the oxide of iron, 
if any, may be separated from the remaining 
liquid by boiling it. It scarcely ever hap- 
pens that any magnesia or lime escapes solu- 
tion in the muriatic acid ; but if it should, 
it will be found in the sulphuric acid ; from 
which it may be separated as directed above 
for the muriatic. This method of analysis is 
sufficiently precise for all common purposes ; 
but if very great accuracy be an object, the 
residuum after the incineration must be treat- 
ed with potash, and in the manner in which 
stones are analyzed, as given in the first part 
of this article. 

9. If the soil contained any salts, or soluble 
vegetable or animal matter, they will be found 
in the water used for separating the sand. 
This water must be evaporated to dryness at 
a heat below boiling. If the solid matter 
left be of a brown colour, and inflammable, 
it may be considered as partly vegetable ex- 
tract. If its smell, when exposed to heat, 
be strong and fetid, it contains animal, mu- 
cilaginous, or gelatinous matter. If it be 
white and transparent, it may be considered 
as principally saline. Nitrate of potash or 
of lime is indicated in this saline matter by 
its sparkling when thrown on burning coals ; 
sulphate of magnesia may be detected by its 
bitter taste ; ai\d sulphate of potash produces 
no alteration in a solution of carbonate of 
ammonia, but precipitates a solution of mu- 
riate of baryta. 

10. If sulphate or phosphate of lime be 
suspected in the soil, a particular process is 
requisite to detect it. A given weight of the 
entire soil, as four hundred grains for in- 
stance, must be mixed with one-third as 



much powdered charcoal, and kept at a red 
heat in a crucible for half an hour. The 
mixture must then be boiled a quarter of an 
hour in half a pint of water, and the solu- 
tion, being filtered, exposed some days to the 
open air. If any notable quantity of sul- 
phate of lime, or gypsum, existed in the soil, 
a white precipitate will gradually form in the 
fluid, and the weight of it will indicate the 
proportion. 

Phosphate of lime, if any be present, may 
be separated from the soil after the process 
for gypsum. Muriatic acid must be digested 
upon the soil in quantity more than sufficient 
to saturate the soluble earths. The solution 
must be evaporated, and water poured upon 
the solid matter. This fluid will dissolve the 
compounds of earths with the muriatic acid, 
and leave the phosphate of lime untouched. 

11. When the examination of a soil is 
completed, the products should be classed, 
and their quantities added together ; and if 
they nearly equal the original quantity of soil, 
the analysis may be considered as accurate. 
It must however be observed, that when phos- 
phate or sulphate of lime is discovered by the 
independent process, No. 10. just mentioned, 
a correction must be made for the general 
process, by subtracting a sum equal to their 
weight from the quantity of carbonate of lime 
obtained by precipitation from the muriatic 
acid. In arranging the products, the form 
should be in the order of the experiments by 
which they are obtained. Thus 400 grains 
of a good siliceous sandy soil may be sup- 
posed to contain 

Gr. 

Of water of absorption, 18 

Of loose stones and gravel, principally 

siliceous, - 42 

Of undecompounded vegetable fibres, 10 
Of fine siliceous sand, - 200 

Of minutely divided matter, separated 

by filtration, and consisting of 
Carbonate of lime, - - 25 
Carbonate of magnesia, - 4 

Matter destructible by heat, prin- 
cipally vegetable, - - 10 
Silex, - - - - 40 
Alumina, 32 

Oxide of iron, . - - 4 
Soluble matter, principally sul- 
phate of potash and vegetable 
extract, 5 

Gypsum, 
Phosphate of lime, 2 

_ 125 



Amount of all the products, 
Loss, - -* 



395 
5 

400 



In this instance the loss is supposed small ; 
but in general, in actual experiments, it will 
L 



ANALYSIS. 



162 



ANALYSIS. 



be found much greater, in consequence of 
the difficulty of collecting the whole quanti- 
ties of the different precipitates ; and when 
it is within thirty for four hundred grains, 
there is no reason to suspect any want of 
due precision in the processes. 

12. When the experimenter is become ac- 
quainted with the use of the different instru- 
ments, the properties of the reagents, and 
the relations between the external and chemi- 
cal qualities of soils, lie will seldom find it 
necessary to perform, in any one case, all the 
processes that have been described. When 
his soil, for instance, contains no notable pro- 
portion of calcareous matter, the action of 
the muriatic acid, No. G. may be omitted : 
in examining peat soils, he will principally 
have to attend to the operation by fire and 
air, No. 7. ; and in the analysis of chalks and 
loams, he will often be able to omit the ex- 
periment with sulphuric acid, No. 8. 

In the first trials that are made by persons 
unacquainted with chemistry, they must not 
expect much precision of result. Many dif- 
ficulties will be met with ; but in overcom- 
ing them the most useful kind of practical 
knowledge will be obtained ; and nothing is 
so instructive in experimental science as the 
detection of mistakes. The correct analyst 
ought to be well grounded in general chemi- 
cal information ; but perhaps there is no bet- 
ter mode of gaining it than that of attempt- 
ing original investigations. In pursuing his 
experiments, he will be continually obliged 
to learn from books the history of the sub- 
stances he is employing or acting upon; and 
his theoretical ideas will be more valuable in 
being connected with practical operation, and 
acquired for the purpose of discovery. 

The analysis of vegetables requires various 
manipulations and peculiar attention, as their 
principles are extremely liable to be altered 
by the processes to which they are subjected. 
It was long before this analysis was brought 
to any degree of perfection. 

Some of the immediate materials of vege- 
tables are separated to our hands by Nature 
in a state of greater or less purity ; as the 
gums, resins, and balsams, that exude from 
plants. The expressed juices contain various 
matters, that may be separated by the appro- 
priate reagents. Maceration, infusion, and 
decoction in water, take up certain parts so- 
luble in this menstruum ; and alcohol will 
extract others that water will not dissolve. 
The mode of separating and extinguishing 
these materials will easily be collected from 
their characters, as given under the head VE- 
GETABLE KINGDOM, and under the different 
articles themselves. 

As the ultimate constituents of all vegeta- 
ble substances are carbon, hydrogen, and oxy- 
gen, with occasionally azote, the problem of 
their final analysis resolves into a method of 
ascertaining the proportion of these elemen- 



tary bodies. MM. Gay Lussac and Thenard 
contrived a very elegant apparatus for vege- 
table and animal analysis, in which the mat- 
ter in a dried state was mixed with chlorate 
of potash, and formed into minute pellets. 
These pellets being projected through the in- 
tervention of a stopcock of peculiar structure 
into an ignited glass tube, were instantly re- 
solved into carbonic acid and water. The 
former product was received over mercury, 
and estimated by its condensation with pot- 
ash ; the latter was intercepted by ignited 
muriate of lime, and was measured by the 
increase of weight which it communicates to 
this substance. By previous trials, the quan- 
tity of oxygen which a given weight of the 
chlorate of potash yielded by ignition was 
known ; and hence the carbon, hydrogen, 
and oxygen, derived from the organic sub- 
stance, as well as the residual azote of the 
gaseous products. 

M. Berzelius modified the above apparatus, 
and employed the organic product in combi- 
nation with a base, generally oxide of lead. 
He mixed a certain weight of this neutral 
compound with a known quantity of pure 
chlorate of potash, and triturated the whole 
with a large quantity of muriate of soda, for 
the purpose of moderating the subsequent 
combustion. This mingled dry powder is 
put into a glass tube about half an inch dia- 
meter, and eight or ten inches long, which is 
partially enclosed in a fold of tin-plate, hoop- 
ed with iron wire. One end of the tube is 
hermetically sealed beforehand, the other is 
now drawn to a pretty fine point by the blow- 
pipe. This termination is inserted into a 
glass globe about an inch diameter, which 
joins it to a long tube containing dry muriate 
of lime in its middle, and dipping at its other 
extremity into the mercury of a pneumatic 
trough. The first tube, with its protecting 
tin case, being exposed gradually to ignition, 
the enclosed materials are resolved into car- 
bonic acid, water, and azote, which come over, 
and are estimated as above described. M. 
Gay Lussac has more recently employed per- 
oxide of copper to mix with the organic sub- 
stance to be analyzed ; because, while it yields 
its oxygen to hydrogen and carbon, it is not 
acted on by azote ; and thus the errors re- 
sulting from the formation of nitric acid with 
the chlorate of potash are avoided. Berzelius 
has afforded satisfactory evidence by his ana- 
lyses, that the simple apparatus which he em- 
ployed is adequate to every purpose of che- 
mical research. Dr Prout has described, in 
the Annals of Philosophy for March 1820, a 
very neat form of apparatus for completing 
analyses of organic substances with the heat 
of a lamp. Hydrogen having the power in 
minute quantities of modifying the constitu- 
tion of the organic bodies, requires to be esti- 
mated with corresponding minuteness. M. 
Porrett has very ingeniously suggested, that 



ANALYSIS. 



163 



ANALYSIS. 



its quantity may be more accurately deter- 
mined by the proportion of oxide of copper 
that is revived, than by the product of water. 
Dilute sulphuric acid being digested on the 
residual cupreous powder, will instantly dis- 
solve the oxide, and leave the reduced metal ; 
whose weight will indicate, by the scale of 
equivalents, the hydrogen expended in its 
reduction. One of hydrogen corresponds to 
nine of water, and to thirty-two of copper. 

From my experiments I find, that this pro- 
posal of M. Porrett will not suit in practice ; 
for much of the peroxide of copper is occa- 
sionally reduced merely to the state of prot- 
oxide. 

Under the different vegetable and animal 
products, we shall take care to state their 
ultimate constituents by the most cqrrect 
and recent analysis. The peculiar substances 
which water, alcohol, ether, and other sol- 
vents, can separate from an organic body, 
may be called the immediate products of the 
vegetable or animal kingdom ; while the car- 
bon, hydrogen, oxygen, and azote, discover- 
able by igneous analysis, are the ultimate con- 
stituent elements. To the former class be- 
long sugar, gum, starch, oils, resins, gelatin, 
urea, organic acids and alkalis, &c. which 
see. 

The following account of my mode of exe- 
cuting the ultimate analysis of organic pro- 
ducts, is extracted from a paper which the 
Royal Society did me the honour to insert in 
their Transactions for 1822. 

The improvements lately introduced into 
the analysis of vegetable and animal com- 
pounds, with the investigation of the equi- 
valent ratios in which their constituent ele- 
ments, carbon, hydrogen, oxygen, and azote, 
are associated, have thrown an unexpected 
light into this formerly obscure province of 
chemical science. While the substitution by 
M. Gay Lussac of black oxide of copper for 
the chlorate of potash, has given peculiar fa- 
cility and elegance to animal analysis, it may 
be doubted whether, in those cases where the 
main object of inquiry is the proportion of 
carbon, it has not frequently led to fallaci- 
ous results. As the quantity of this element 
is inferred from the volume of carbonic acid 
evolved in the decomposition of the organic 
matters, such of their particles as happen not 
to be in immediate contact with the cupreous 
oxide, will remain unconverted into carbonic 
acid ; and thus the proportion of carbon will 
come to be underrated ; an accident which 
cannot occur with chlorate of potash, since 
the carbonaceous matter is here plunged in 
an ignited atmosphere of oxygen. It is pro- 
bably to this cause that we must refer the 
discrepant results, in the analysis of pure 
sugar, between MM. Gay Lussac, Thenard, 
and Berzelius, on the one hand, and Dr Prout 
on the other ; the former gentlemen assign- 
ing about 43 parts in the hundred of car- 



bon, while the latter states the carbon at only 

The objects of the present paper are, first, 
to indicate, and endeavour to remove, several 
sources of fallacy attending the method with 
peroxide of copper ; and next, to exhibit the 
results of its application to a considerable 
series of vegetable and animal compounds. 

Peroxide of copper, prepared by igniting 
the pure nitrate of this metal, is, like yellow 
oxide of lead, and many other metallic oxides, 
readily absorbent of a small portion of hu- 
midity from the air, the quantity of which 
depends, in some measure, on the length of 
time during which it has suffered ignition. 
If exposed to a red heat merely till the va- 
pours of nitric acid are expelled, 100 grains 
of the oxide will absorb, in the ordinary state 
of the atmosphere, from 1-1 Oth to 2-10ths 
of a grain of moisture in the space of an hour 
or two, and about one-half of the above 
quantity in a very few minutes. The French 
chemists, who have operated most with this 
agent, seem to be well aware of this circum- 
stance, for they direct the peroxide to be used 
immediately after ignition, and to be tritu- 
rated with the organic matter in a hot mor- 
tar of agate or glass. Yet this precaution will 
not entirely prevent the fallacy arising from 
the hygrometric action ; for I find that per- 
oxide thus treated does absorb, during the 
long trituration essential to the process, a 
certain quantity of moisture, which, if not 
taken into account, will produce serious er- 
rors in the analytical results. It is better 
therefore to leave the powdered peroxide in- 
tended for research exposed for such time to 
the air as to bring it to hygrometric repose, 
then to put it up in a phial, and by igniting 
one hundred grains of it in a proper glass 
tube, sealed at one end, and loosely closed 
with a glass plug at the other, to determine 
the proportion of moisture which it contains. 
This, then, indicates the constant quantity to 
be deducted from the loss of weight which 
the peroxide suffers in the course of the ex- 
periment. The mortar should be perfectly 
dry, but not warm. 

Experimenters have been at great pains to 
bring the various organic objects of research 
to a state of thorough desiccation before mix- 
ing them with the peroxide of copper ; but 
this practice introduces a similar fallacy to 
that above described. We ought, therefore, 
after having made them as dry as possible by 
the joint agencies of heat and an absorbent 
surface of sulphuric acid in vacuo, to expose 
them to the air till they also come into hy- 
grometric repose, noting the quantity of mois- 
ture which they imbibe, that it may be after- 
wards allowed for. The plan which I adopt 
for the purpose of desiccation seems to an- 
swer very well. Having put the pulverulent 
animal or vegetable matter into short phials, 
furnished with ground glass stoppers, I place 



ANALYSIS. 



164 



ANALYSIS. 



the open phials in a large quantity of sand, 
heated to 212 F. in a porcelain capsule, and 
set this over a surface of sulphuric acid in an 
exhausted receiver. After an hour or more 
the receiver is removed, and the phials in- 
stantly stopped. The loss of weight shews 
the total moisture which each of them has 
parted with ; while the subsequent increase 
of their weight, after leaving them unstopped 
for some time in the open air, indicates the 
amount of hygrometric absorption. This is 
consequently the quantity to be deducted in 
calculating experimental results. 

Many chemists, particularly in this coun- 
try, have employed the heat of a spirit-lamp, 
instead of that produced by the combustion 
of charcoal, for igniting the tube in which 
the mixed materials are placed. I have com- 
pared very carefully both methods of heating, 
and find that for many bodies, such as coal 
and resin, which abound in carbon, the flame 
of the lamp is insufficient ; while its applica- 
tion being confined at once to a small portion 
of the tube, that uniform ignition of the 
whole, desirable towards the close of the ex- 
periment, cannot be obtained. I was hence 
led to contrive a peculiar form of furnace, in 
which, with a handful of charcoal reduced 
to bits about the size of small filberts, an 
experiment may be completed without anxie- 
ty or trouble, in the space of half an hour. 
Since I have operated with this instrument, 
the results on the same body have been much 
more consistent than those previously obtain- 
ed with the lamp ; and it is so convenient, 
that I have sometimes finished eight experi- 
ments in a day. 

Fig. 1. (Plate VI.) represents the whole 
apparatus, as when in action. Fig. 2. is a 
horizontal section of the furnace, in which we 
perceive a semi-cylinder of thin sheet-iron, 
about eight inches long and 3 wide, perfo- 
rated with holes, and resting on the edge of 
a hollow prism of tin-plate, represented more 
distinctly in fig. 3. where n shews a slit, 
through which the sealed end of the glass 
tube may be made to project, on occasion. 
i is a handle attached to the semi-cylinder, by 
which it may be slid backwards or forwards, 
and removed at the end of the process, d is 
a sheath of platinum foil, which serves, by 
aid of a wire laid across, to support the mid- 
dle of the tube, when it is softened by igni- 
tion. At g, the plates which close the ends 
of the semi-cylinder and tin-plate prism, rise 
up a few inches to screen the pneumatic ap- 
paratus from the heat. A third occasional 
screen of tin-plate is hung on at^ All these 
are furnished with slits for the passage of the 
glass tube. This is made of crown glass, and 
is generally about nine or ten inches long, 
and 3-10ths of internal diameter. It is con- 
nected with the mercurial cistern by a nar- 
row tube and caoutchouc collar. This tube 
has a syphon form, and rises about an inch 



within the graduated receiver at e. By this 
arrangement, should the collar be not abso- 
lutely air-tight, the pressure of the column of 
mercury causes the atmospheric air to enter 
at the crevice, and bubbles of it will be seen 
rising up without the application of heat. 
At the end of the operation, the point of the 
tube e is always left above the surface of the 
mercury, the quantity of organic matter em- 
ployed being such as to produce from six to 
seven cubic inches of gaseous product, the 
volume of the graduated receiver being seven 
cubic inches. 

As the tubes with which I operate have all 
the same capacity, viz. half a cubic inch ; and 
as the bulk of materials is the same in all the 
experiments, one experiment on the analysis 
of sugar or resin gives the volume of atmo- 
spheric air due to the apparatus ; which vo- 
lume is a constant quantity in the same cir- 
cumstances of ignition. And since the whole 
apparatus is always allowed to cool to the 
atmospheric temperature, the volume of resi- 
dual gas in the tubes comes to be exactly 
known, being equal, very nearly, to the pri- 
mitive volume of atmospheric air left after 
the absorption of the carbonic acid in the su- 
gar or resin experiment.* Thus this quantity, 
hitherto ill appreciated or neglected in many 
experiments, though it is of very great conse- 
quence, may be accurately found. At k, fig. 
2. a little tin-plate screen is shewn. It is per- 
forated for the passage of the tube, and may 
be slid along, and left at any part of the se- 
mi-cylindric cage, so as to preserve from the 
influence of the beat any requisite portion of 
the sealed end of the tube. At fig. 4. is 
seen the shape of the little bulb, into which 
I introduce the proper weight of ether, alco- 
hol, naphtha, or other volatile liquids which 
are destined for analysis. After weighing it 
exactly, it is immediately slid down to the 
bottom of the tube, and covered with 1 50 or 
200 grains of peroxide of copper. The bulb 
has a capacity equal to 3 grain measures of 
water, and its capillary point is sometimes 
closed with an inappreciably small quantity 
of bees- wax, to prevent the exhalation of tire 
liquid till the peroxide be ignited. 

6 is a cover to the furnace, with an oblong 
orifice at its top. It serves for a chimney, 
and may be applied or removed by means of 
its handle, according as we wish to increase 
or diminish the heat, cc are tin cases en- 
closing corks, through which the iron wires 
are passed that support the whole furnace at 
any convenient height and angle of inclina- 
tion. 

The tightness of the apparatus at the end 
of the process is proved by the rising of the 



* If a be the capacity of the graduated receiver, 
and b the spare capacity of the tubes, then the above 

volume is b . 

a + b 



ANALYSIS. 



165 



ANALYSIS. 



mercury in the graduated receiver by about 
one-tenth of an inch, as the tube becomes 
refrigerated. 

My mode of operating with the peroxide 
of copper is the following : 

I triturate very carefully, in a dry glass 
mortar, from i to 2^ grains of the matter to 
be analyzed, with from 100 to 140 grains of 
the oxide. I then transfer it, by means of a 
platinum-foil tray and small glass funnel, 
into the glass tube, clearing out the mortar 
with a metallic brush. Over that mixture I 
put 20 or 30 grains of the peroxide itself, 
and next, 50 or 60 grains of clean copper 
filings. The remaining part of the tube is 
loosely closed with 10 or 12 grains of amian- 
thus, by whose capillary attraction the mois- 
ture evolved in the experiment is rapidly 
withdrawn from the hot part of the tube, and 
the risk of its fracture thus completely obvi- 
ated. The amianthus serves moreover as a 
plug, to prevent the projection of any minute 
particles of filings, or of oxide when the fil- 
ings are not present. The tube is now weigh- 
ed in a very delicate balance, and its weight 
is written down. A little cork, channelled 
at its side, is next put into the tube, to pre- 
vent the chance of mercury being forced 



backwards into it, by any accidental cooling 
or condensation. The collar of caoutchouc 
is finally tied on, and the tube is placed, as 
is shewn in fig. 2. but without the plate k t 
which is employed merely in the case of ana- 
lyzing volatile liquids. A few fragments of 
ignited charcoal are now placed under the 
tube, at the end of the furnace next to the 
cistern, and the remaining space in the semi- 
cylinder is filled up with bits of cold charcoal. 
The top, b, may then be put in its place, 
when the operation will proceed spontaneous- 
ly ; the progressive advance of the ignition 
from one end to the other being proportioned 
to the expansion of glass, so that the tube 
very seldom cracks in the process. Indeed 
I have often used the same tube for a dozen 
experiments, in the course of which it be- 
came converted into vitrite, or Reaumur's 
porcelain. 

Since the evolved gas is saturated with 
moisture, I reduce it to the volume of dry 
gas by help of the following table, computed 
by the well known formula from my table of 
the elastic force of steam, which the Royal 
Society did me the honour to publish in their 
Transactions for the year 1818. 



Temper- 
ature. 


Multiplier. 


Temper- 
ature. 


Multiplier. 


Temper- 
ature. 


Multiplier. 


53 F. 
54 
55 
56 
57 
58 
59 


0.9870 
0.9864 
0.9858 
0.9852 
0.9846 
0.9839 
0.9833 


60 F. 
61 
62 
63 
64 
65 
66 


0.9827 
98.20 
98.13 
98.06 
97.99 
97.93 
97.86 


67 F. 
68 
69 
70 
71 
72 
73 


97.79 
97.72 
97.65 
0.9758 
0.9751 
0.9743 
0.9735 



In certain cases, where the quantity of hy- 
drogen is small, or where, as in the example 
of indigo, its presence has been denied, I em- 
ploy pulverulent protochloride of mercury 
(calomel) instead of peroxide of copper. The 
organic compound being intimately mixed 
with that powder, and gently heated, the mu- 
riatic acid gas obtained demonstrates the pre- 
sence, though half of its volume will not give 
the total quantity, of hydrogen ; for a propor- 
tion of this elementary body continues associ- 
ated with oxygen in the state of water. Dry 
oxalate of lead, treated in this way, yields 
not the slightest trace of muriatic acid; for, on 
passing the disengaged gas through a dilute 
solution of nitrate of silver, no precipitation 
or even cloud of chloride is produced. But 
five grains of indigo, prepared from the de- 
oxidized solution of the dyer's vat, and freed 
from its lime and resin by the successive ap- 
plication of dilute muriatic acid and alcohol, 
gave five cubic inches of muriatic acid gas 
when heated along with 150 grains of calo- 
mel. Hers we have a quantity of gas equi- 



valent to 2^ cubic inches of hydrogen. By 
means of peroxide of copper, however, nearly 
4 times the above quantity of hydrogen may 
be obtained from the same weight of indigo. 

I shall now give in detail one example of 
the mode of computing the relation of the 
constituents from the experimental results, 
and shall then state the other analysis in a 
tabular form, subjoining a few remarks on 
the habitudes of some peculiar bodies. 

1.4 grains of sulphuric ether, specific gra- 
vity 0.70, being slowly passed in vapour from 
the glass bulb through 200 grains of ignited 
peroxide of copper, yielded 6.8 cubic inches 
of carbonic acid gas at 66 F. which are 
equivalent to 6.57128 of dry gas at 60. 
This number being multiplied by 0.127 = 
the carbon in one cubic inch of the gas, the 
product 0.8345256, is the carbon in 1.4 
grains of ether; and 0.8345256 X | = 
2.2254 = the oxygen equivalent to the car- 
bonic acid. The tube was found to have 
lost 4.78 grains in weight, 0.1 of which was 
due to the hygrometric moisture in the oxide, 



ANATASE. 



166 



ANHYDRITE. 



and 1.4- to the ether. The remainder, 3.28, 
is the quantity of oxygen abstracted from the 
oxide by the combustible elements of the 
ether. But of these 3.28 grains, 2.2254 
went to the formation of the carbonic acid, 
leaving 1.0546 of oxygen, equivalent to 
0.1318 of hydrogen. Hence, 1.4 ether, by 
this experiment, which is taken as the most 
satisfactory of a great number, seem to con- 
sist of 

Carbon, 0.8345 

Hydrogen, 0.1318 

Water, 0.4337 

1.4000 

And in 1 grain we shall have,- 
Carbon, 0.5960 3 atoms 2.25 60.00 
Hydrogen, 0.1330 4 atoms 0.50 13.33 
Oxygen, 0.2710 1 atom 1.00 26.66 



1.0000 a75 100.0 

Or, 3 vols olef. gas = 3 X 0.9722 = 2.9166 
2 vap. of water, 2 X 0.625 = 1 .25 

4. 1666 

The proportion of the constituents of sul- 
phuric ether, deduced by M. Gay Lussac 
from the experiments of M. Th. de Saussure, 
are 2 volumes olefiant gas -{- 1 volume va- 
pour of water, which 3 volumes are condensed 
into 1 of vapour of ether, having a specific 
gravity s= 2.58. The ether which I used 
had been first distilled off dry carbonate of 
potash, and then digested on dry muriate of 
lime, from which it was simply decanted, ac- 
cording to the injunction of M. de Saussure. 
Whether my ether contained more alcoholic 
matter than that employed by the Genevese 
philosopher, or whether the difference of re- 
sult is to be ascribed to the difference in the 
mode of analysis, must be decided by future 
researches. 

By analogous modes of reduction, the re- 
sults were deduced from my experiments. I 
ought here to state, that in many cases the 
materials, after being ignited in the tube, and 
then cooled, were again triturated in the mor- 
tar, and subjected to a second ignition. Thus, 
none of the carbon could escape conversion 
into carbonic acid. I was seldom content 
with one experiment on a body ; frequently 
six or eight were made. 

ANATASE. Octohedrite, oxide of tita- 
nium rutile, and titane rutile. This mineral 
shews a variety of colours by reflected light, 
from indigo blue to reddish-brown. By 
transmitted light it appears greenish-yellow. 
It is found usually in small crystals, octohe- 
drons, with isosceles triangular faces. Struc- 
ture lamellar; it is semitransparent or opaque; 
fragments splendent, adamantine; scratches 
glass; brittle ; sp. gr. 3. 85. It is a pure oxide 
of titanium. It has been found only in Dau- 
phiny and Norway ; and is a very rare mine- 



ral. It occurs in granite, gneiss, mica slate, 
and transition lime-stone. 

ANDALUSITE. A massive mineral, 
of a flesh, and sometimes rose-red colour. 
It is, however, occasionally crystallized in 
rectangular four- sided prisms, verging on 
rhomboids. The structure of the prisms is 
lamellar, with joints parallel to their sides. 
Translucent; scratches quartz; is easily 
broken; sp. gr. 3.165. Infusible by the 
blowpipe; in which respect it differs from 
felspar, though called felspath apyre by Haiiy. 
It is composed of 52 alumina, 32 silica, 8 
potash, 2 oxide of iron, and 6 loss. Vauq. 
It belongs to primitive countries, and was 
first found in Andalusia in Spain. It is found 
in mica slate in Aberdeenshire, and in the 
Isle of Unst ; Dartmoor in Devonshire ; in 
mica slate at Killiney, near Dublin, and at 
Douce Mountain, county Wicklow. 

ANDREOLITE. See HARMOTOME. 

ANHYDRITE. Anhydrous gypsum. 
There are six varieties of it : 

1. Compact; has various shades of white, 
blue, and red ; massive and kidney-shaped ; 
dull aspect ; splintery or conchoidal fracture ; 
translucent on the edges; is scratched by 
fluor, but scratches calc spar; somewhat 
tough ; specific gravity 2.850. It is dry sul- 
phate of lime, with a trace of sea salt. It is 
found in the salt mines of Austria and Salz- 
burg, and at the foot of the Harz mountains. 

2. Granular ; the scaly of Jameson, is found 
in massive concretions, of which the structur? 
is confusedly foliated. White or bluish 
colour, of a pearly lustre; composition as 
above, with one per cent of sea salt. It oc- 
curs in the salt mines of Halle ; sp. gr. 2.957. 

3. Fibrous; massive, glimmering, pearly 
lustre; fracture in delicate parallel fibres; 
scarcely translucent ; easily broken. Found 
at Halle, Ischel, and near Brunswick. 

4. Radiated. Blue sometimes spotted with 
red; radiated, splendent fracture; partly 
splintery; translucent; not hard; sp. gr. 
2.940. 5. Sparry, or cube spar. Milk- 
white colour, passing sometimes into greyish 
and reddish- white ; short four-sided prisms, 
having two of the opposite sides much broader 
than the other two ; and occasionally the la- 
teral edges are truncated, whence results an 
eight-sided prism ; lustre splendent, pearly; 
foliated fracture; threefold rectangular cleav- 
age; cubical fragments; translucent; scratch- 
es calc spar; brittle; sp. gr. 2.9. This re 
the muriacite of some writers. It is doubly 
refracting. It is said to contain one per cent 
of sea salt. It is found at Bex in Switzer- 
land, and Halle in the Tyrol. 6. Silicife- 
rous, or vulpinite. Massive concretions of 
a laminated structure; translucent on the 
edges; splendent and brittle; greyish- white 
veined with bluish-grey; sp. gr. 2.88. It 
contains eight per cent silex ; the rest is sul- 
phate of lime. It is called by statuaries, 



ANIMAL KINGDOM. 



167 



ANNEAL. 



Marmo bardiglio di Bergamo, and takes a 
fine polish. It derives its name from Vul- 
pino in Italy, where it accompanies lime. 

ANHYDROUS. Destitute of water. 

ANIL, or NIL. This plant, from the 
leaves of which indigo is prepared, grows in 
America. 

ANIMAL KINGDOM. Animal bodies 
may be considered as peculiar apparatus for 
carrying on a determinate series of chemical 
operations. Vegetables seem capable of ope- 
rating with fluids only, and at the temperature 
of the atmosphere. But most animals have 
a provision for mechanically dividing solids 
by mastication, which answers the same pur- 
pose as grinding, pounding, or levigation does 
in our experiments ; that is to say, it enlarges 
the quantity of surface to be acted upon by 
solvents. The process carried on in the 
stomach appears to be of the same kind as 
that which we distinguish by the name of di- 
gestion ; and the bowels, whatever other uses 
they may serve, evidently form an apparatus 
for filtering or conveying oflf the fluids; 
while the more solid parts of the aliments, 
which are probably of such a nature as not 
to be rendered fluid, but by an alteration 
which would perhaps destroy the texture of 
the machine itself, are rejected as useless. 
When this filtered fluid passes into the circu- 
latory vessels, through which it is driven with 
considerable velocity by the mechanical action 
of the heart, it is subjected not only to all 
those changes which the chemical action of 
its parts is capable of producing, but is like- 
wise exposed to the air of the atmosphere in 
the lungs, into which that elastic fluid is ad- 
mitted by the act of respiration. Here it 
undergoes a change of the same nature as 
happens to other combustible bodies, when 
they combine with its vital part, or oxygen. 
This vital part becomes condensed, and com- 
bines with the blood, at the same time that it 
gives out a large quantity of heat, in conse- 
quence of its own capacity for heat being di- 
minished. A small portion of azote likewise 
is absorbed, and carbonic acid is given out. 
Some curious experiments of Spallanzani 
shew, that the lungs are not the sole organs 
by which these changes are effected. Worms, 
insects, shells of land and sea animals, egg 
shells, fishes, dead animals, and parts of ani- 
mals, even after they have become putrid, are 
capable of absorbing oxygen from the air, and 
giving out carbonic acid. They deprive at- 
mospheric air of its oxygen as completely as 
phosphorus. Shells, however, lose this pro- 
perty when their organization is destroyed by 
age. Amphibia, deprived of their lungs, 
lived much longer in the open air, than others 
in air destitute of oxygen. It is remarkable, 
that a larva, weighing a few grains, would 
consume almost as much oxygen in a given 
time, as one of the amphibia a thousand times 
its bulk. 



The following are the peculiar chemical 
products of animal organization : Gelatin, 
albumen, fibrin, fat, caseous matter, colouring 
matter of blood, mucus, urea, picromel, osma- 
zome, sugar of milk, and sugar of diabetes. 
(See also the list of ACIDS ORGANIC, for seve- 
ral animal products). The compound animal 
products are the various solids and fluids, 
whether healthy or morbid, that are found in 
the animal body ; such as muscle, skin, bone, 
blood, urine, bile, morbid concretions, brain, 
&c. 

When animal substances are left exposed 
to the air, or immersed in water or other 
fluids, they suffer a spontaneous change, 
which is more or less rapid according to cir- 
cumstances. The spontaneous change of or- 
ganized bodies is distinguished by the name 
of fermentation. In vegetable bodies there 
are distinct stages or periods of this process, 
which have been divided into the vinous, 
acetous, and putrefactive fermentations. Ani- 
mal substances are susceptible only of the two 
latter, during which, as in all other sponta- 
neous changes, the combinations of chemical 
principles become in general more and more 
simple. There is no doubt but much instruc- 
tion might be obtained from accurate obser- 
vations of the putrefactive processes in all 
their several varieties and situations ; but the 
loathsomeness and danger attending on such 
inquiries have hitherto greatly retarded our 
progress in this department of chemical 
science. See FERMENTATION (PUTREFAC- 
TIVE). 

ANIME, improperly called gum-anime, 
is a resinous substance imported from New 
Spain and the Brazils. There are two kinds, 
distinguished by the names of oriental and 
occidental. The former is dry, and of an un- 
certain colour, some specimens being green- 
ish, some reddish, and some of the brown 
colour of myrrh. The latter is in yellow- 
ish-white, transparent, somewhat unctuous 
tears, and partly in larger masses ; brittle, of 
a light pleasant taste, easily melting in the 
fire, and burning with an agreeable smell. 
Like resins, it is totally soluble in alcohol, 
and also in oil. Water takes up about l-16th 
of the weight of this resin by decoction. The 
spirit, drawn off by distillation, has a con- 
siderable degree of the taste and flavour of 
the anime ; the distilled water discovers on 
its surface some small portion of essential oil. 

This resin is used by perfumers, and also 
in certain plasters, wherein it has been sup- 
posed to be of service in nervous affections of 
the head and other parts ; but there are no 
reasons to think, that, for medical purposes, 
it differs from common resins. 

ANNEAL. We know too little of the 
arrangement of particles, to determine what 
it is that constitutes or produces brittleness 
in any substance. In a considerable number 
of instances of bodies which are capable of 



ANORTHITE. 



168 



ANTIMONY. 



undergoing ignition, it is found that sudden 
cooling renders them hard and brittle. This 
is a real inconvenience in glass, and also in 
steel, when this metallic substance is required 
to be soft and flexible. The inconveniencies 
are avoided by cooling them very gradually ; 
and this process is called annealing. Glass 
vessels, or other articles, are carried into an 
oven or apartment near the great furnace, 
called the leer, where they are permitted to 
cool, in a greater or less time, according to 
their thickness and bulk. The annealing of 
steel, or other metallic bodies, consists simply 
in heating them, and suffering them to cool 
again, either upon the hearth of the furnace, 
or in any other situation where the heat is 
moderate, or at least the temperature is not 
very cold. 

ANNOTTO. The pellicles of the seeds 
of the bixa orellana, a liliaceous shrub, from 
15 to 20 feet high in good ground, afford the 
red masses brought into Europe under the 
name of Annotto, Orlean, and Roucou. 

The annotto commonly met with among us 
is moderately hard, of a brown colour on the 
outside, and a dull red within. It is diffi- 
cultly acted upon by water, and tinges the 
liquor only of a pale brownish-yellow colour. 
In rectified spirit of wine it very readily dis- 
solves, and communicates a high orange or 
yellowish-red. Hence it is used as an ingre- 
dient in varnishes, for giving more or less of 
an orange cast to the simple yellows. 

Sulphuric ether is the best solvent of an- 
notto. Potash and soda, either caustic or 
carbonated, dissolve annotto in great quanti- 
ties; from which solutions it is thrown down 
by acids in small flocks. The alkaline solu- 
tions are of a deep red colour. Chlorine de- 
colours the alcoholic solution of annotto ; the 
liquor becoming speedily white and milky. 
If strong sulphuric acid be poured on annotto 
in powder, the red colour passes immediately 
to a very fine indigo blue : but this tint is not 
permanent ; it changes to green, and finally 
to violet, in the course of 24 hours thereafter. 
This property of becoming blue belongs also 
to saffron. Nitric acid, slightly heated on 
annotto, sets it on fire ; and a finely divided 
charcoal remains. Annotto is soluble both 
in essential oils, as oil of turpentine, and in 
fixed oils. Boussingault, Ann. de Chim. et 
de Phys. xxviii. 440. 

Beside its use in dyeing, it is employed for 
colouring cheese. 

ANORTHITE. The primitive form of 
this mineral is a doubly oblique prism. The 
lustre of the cleavages is pearly, and that of 
the conchoidal fracture vitreous. The crystals 
of anorthite are clear and transparent, but 
small. Sp. gr. 763. Strong muriatic acid 
entirely decomposes it. It consists of silica 
44.49, alumina 34.46, oxide of iron 0.74, 
lime 15.68, magnesia 5.26. Rose. The 
name anorthite, signifying without right an- 



gles, distinguishes it from felspar, two of 
whose cleavages are at right angles to each 
other. 

ANTHOPHYLLITE. A massive mi- 
neral of a brownish colour ; sometimes also 
crystallized in thin flat six-sided prisms, 
streaked lengthways. It has a false metallic 
lustre, glistening and pearly. In crystals, 
transparent. Massive ; only translucent on 
the edges. It does not scratch glass, but 
fluateoflime. Specific gravity 3.2. Some- 
what hard, but exceedingly brittle. Infusible 
alone before the blowpipe, but with borax it 
gives a grass-green transparent bead. It con- 
sists of 56 silica, 13. 3 alumina, 14 magnesia, 
3.33 lime, 6 oxide of iron, 3 oxide of man- 
ganese, 1 .43 water, and 2. 94 loss, in 100. It 
is found at Konigsberg in Norway. 

ANTHRACITE. Blind coal, Kilkenny 
coal, or glance coal. There are three varieties. 
1. Massive, the conchoidal of Jameson. Its 
colour is iron-black, sometimes tarnished on 
the surface, with a splendent metallic lustre. 
Fracture conchoidal, with a pseudo-metallic 
lustre. It is brittle and light. It yields no 
flame, and leaves whitish ashes. It is found 
in the newest floetz formations, at Meissner 
in Hesse, and Walsall in Staffordshire. 2. 
Slaty anthracite. Colour black, or brownish- 
black. Imperfect slaty in one direction, with 
a slight metallic lustre. Brittle. Specific 
gravity 1.4 to 1.8. Consumes without flame. 
It is composed of 72 carbon, 13 silica, 3.3 
alumina, and 3.5 oxide of iron. It is found 
in both primitive and secondary rocks : at 
Calton Hill, Edinburgh ; near Walsall, Staf- 
fordshire; in the southern parts of Breck- 
nockshire, Carmarthenshire, and Pembroke- 
shire, whence it is called Welsh culm ; near 
Cumnock and Kilmarnock, Ayrshire ; and 
most abundantly at Kilkenny, Ireland. 3. 
Columnar anthracite. In small short pris- 
matic concretions, of an iron-black colour, 
with a tarnished metallic lustre. It is brittle, 
soft, and light. It yields no flame or smoke. 
It forms a thick bed near Sanquhar in Dum- 
fries-shire ; at Saltcoats and New Cumnock 
in Ayrshire. It occurs also at Meissner in 
Hesse. 

ANTIMONY. The word antimony is 
used in commerce to denote a metallic ore, 
consisting of sulphur combined with the metal 
which is properly called Antimony. Some- 
times this sulphuret is termed crude anti- 
mony, to distinguish it from the pure metal, 
or regulus, as it was formerly called. 

Antimony is of a dusky-white colour, very 
brittle, and of a plated or scaly texture. Its 
specific gravity, according to M. Brisson, is 
6.7021, but Bergman makes it 6.86. Soon 
after ignition, about 800 F., it melts, and by 
a continuance of the heat it becomes oxidized, 
and rises in white fumes, which may after- 
ward be volatilized a second time, or fused 
into a hyacinthine glass, according to the 



ANTIMONY. 



169 



ANTIMONY. 



management of the heat. The first .were for- 
merly called argentine flowers of regulus of 
antimony. In closed vessels the antimony 
rises totally without decomposition. This 
metallic substance is not subject to rust by 
exposure to air, though its surface becomes 
tarnished by that means. 

There are certainly three, possibly four dis- 
tinct combinations of antimony and oxygen. 
1. The protoxide of Berzelius is a blackish- 
grey powder, obtained from a mixture of pow- 
der of antimony and water at the positive pole 
of a voltaic circuit. Heat enables this oxide 
to absorb oxygen rapidly, con verting it into the 
tritoxide. According to Berzelius, it consists 
of 100 of metal and 4-. 65 oxygen. It must 
be confessed, however, that the data for fix- 
ing these proportions are very doubtful. 2. 
The deutoxide may be obtained by digesting 
the metal in powder in muriatic acid, and 
pouring the solution into water of potash. 
Wash and dry the precipitate. It is a pow- 
der of a dirty- white colour, which melts at 
a moderate red heat, and crystallizes as it 
cools. According to Berzelius, it consists of 
84.3 metal + 15.7 oxygen. 3. The trit- 
oxide, or antimonious acid, is the immediate 
product of the combustion of the metal, 
called of old, from its fine white colour, the 
argentine flowers of antimony. It may also 
be formed by digesting hot nitric acid on 
antimony. When fused with one-fourth of 
antimony, the whole becomes deutoxide. It 
forms the salts called antimonites with the 
different bases. According to Berzelius, the 
tritoxide consists of about 80 metal -}- 20 
oxygen. 4. The peroxide, or antimonic acid, 
is formed when the metal in powder is ignited 
along with six times its weight of nitre in a 
silver crucible. The excess of potash and 
nitre being afterwards separated by hot water, 
the antimoniate of potash is then to be de- 
composed by muriatic acid, when the insolu- 
ble antimonic acid of a straw colour will be 
obtained. Nitro-muriatic acid likewise con- 
verts the metal into the peroxide. Though 
insoluble in water, it reddens the vegetable 
blues. It does not combine with acids. At 
a red heat oxygen is disengaged, and anti- 
monious acid results. Berzelius infers its 
composition to be 76.34 metal -J- 23.66 
oxygen. It is difficult to reconcile the above 
three portions of oxygen to one prime equi- 
valent for antimony. The number 1 1 gives 
ti-e best approximation to Berzelius's analy- 
ses. - We shall then have the 

In 100 parts. 

Deutoxfd- 1 1 metal + 2oxy. or 84.6 + 15.4 
Tritoxide 11 +3 78.6 -f- 21.4 

Peroxide 11 + 4 73. 4 + 26. 6 

The first oxide is too imperfectly known 
to enter into the argument. 

M. Rose of Berlin has ascertained the 
existence of three sulphurets of antimony. 
The native mineral dissolves entirely mu- 



riatic acid, disengaging only sulphuretted 
hydrogen. It is also formed by passinf 
sulphuretted hydrogen through solution of 
emetic tartar, or through butter of antimony 
dissolved in water and tartaric acid. It is in 
this case of an orange colour, but is a simple 
sulphuret, as is also, according to him, kermes 
mineral. The latter substance yielded him, 
in 100 parts, 72.32 antimony -f- 27.68 sul- 
phur. Now the native sulphuret by Berze- 
lius contains 72.86 + 27.14; a near ap- 
proximation. This seems to consist of 11 
metal -f- 4 sulphur, or to be a bisulphuret. 
The next sulphuret has an orange colour, 
which resembles a good deal the golden sul- 
phuret. It is formed by passing sulphuretted 
hydrogen through a solution of antimonious 
acid. The best way of procuring antimo- 
nious acid in solution, is to dissolve antimony 
in aqua regia, and to evaporate the solution 
to dryness. The antimonic acid thus formed 
is then ignited, to convert it into antimonious 
acid; which is to be melted with caustic 
potash, and the fused mass is to be treated 
with hydrochloric acid and water, till a clear 
liquor be obtained. The sulphuret formed 
as above from this solution consists of 66.35 
metal -}- 33.65 sulphur. The third sulphu- 
ret is the sulphur antimonii auratum, of 
which no analysis is given. Ann. de Chim. 
1825. 

Chlorine gas and antimony combine with 
combustion, and a bichloride results. This 
was formerly prepared by distilling a mixture 
of two parts of corrosive sublimate with one 
of antimony. The substance which came 
over, having a fatty consistence, was called 
butter of antimony. It is frequently crys- 
tallized in four-sided prisms. It is fusible 
and volatile at a moderate heat ; and is re- 
solved by water alone into the white oxide 
and muriatic acid. Being a bichloride, it is 
eminently corrosive, like the bichloride of 
mercury, from which it is formed. It con- 
sists of 45.7 chlorine -f- 54.3 antimony, 
according to Dr John Davy's analysis, when 
the composition of the sulphuret is corrected 
by its recent exact analysis by Berzelius. 
But 11 antimony -\- 2 primes chlorine =r 
9.0, give the proportion per cent of 44. 1 -|- 
55.5; a good coincidence, if we consider the 
circuitous process by which Dr Davy's ana- 
lysis was performed. Three parts of corro- 
sive sublimate, and one of metallic antimony, 
are the equivalent proportions for making 
butter of antimony. 

Iodine and antimony combine by the aid 
of heat into a solid iodide, of a dark red 
colour. 

The phosphuret of this metal is obtained 
by fusing it with solid phosphoric acid. It 
is a white semi-crystalline substance. 

The sulphuret of antimony exists abun- 
dantly in nature. ( See ORES of ANTIMONY. ) 
It consists, according to Berzelius, of 100 



ANTIMONY. 



170 



ANTIMONY. 



antimony-}- 37.25 sulphur. The propor- 
tion given by the above equivalent ratio is 
100 + 36.5. Other analysts have found 
30, 33, and 35, to 100 of metal. Berzelius 
admits that there may be a slight error in 
his numbers. 

The only important alloys of antimony are 
those of lead and tin : the former constitutes 
type metal, and contains about one-sixteenth 
of antimony ; the latter alloy is employed for 
making the plates on which music is engraved. 
When this alloy is acted on by nitric acid 
with heat, the tin, in becoming an insoluble 
oxide, carries down with it the antimony, ac- 
cording to M. Bussolin. 

The salts of antimony are of two differ- 
ent orders: in the first, the deutoxide acts 
the part of a sulifinble base ; in the second, 
the tritoxide and peroxide act the part of 
acids, neutralizing the alkaline and other 
bases, to constitute the antimonites and anti- 
moniates. 

The only distinct combination of the first 
order entitled to our attention, is the triple 
salt called tartrate of potash and antimony, 
or tartar emetic, and which, by M. Gay Lus- 
sac's new views, would be styled cream-tar- 
trate of antimony. This constitutes a valu- 
able and powerful medicine, and therefore 
the mode of preparing it should be correctly 
and clearly defined. As the dull white 
deutoxide of antimony is the true basis of 
this compound salt, and as that oxide readily 
passes by mismanagement into the tritoxide 
or antimonious acid, which is altogether un- 
fit for the purpose, adequate pains should be 
taken to guard against so capital an error. 
In former editions of the British Pharmaco- 
poeias, the glass of antimony was prescribed 
as the basis of tartar emetic. More complex 
and precarious formulae have been since in- 
troduced. The new edition of the Pharma- 
copee Fran9aise has given a recipe, which 
appears, with a slight change of proportions, 
to be unexceptionable : Take of the sulphu- 
retted vitreous oxide of antimony, levigated 
and acidulous tartrate of potash, equal parts. 
Form a powder, which is to be put into an 
earthen or silver vessel, with a sufficient 
quantity of pure water. Boil the mixture 
for half an hour, adding boiling water from 
time to time ; filter the hot liquor, and eva- 
porate to dryness in a porcelain capsule ; 
dissolve in boiling water the result of the 
evaporation ; evaporate till the solution ac- 
quires the sp. grav. 1.161, and then let it 
repose, that crystals be obtained, which, by 
this process, will be pure. By another re- 
cipe, copied, with some alteration, from Mr 
Philips's prescription, into the Appendix of 
the French Pharmacopoeia, a subsulphate of 
antimony is formed first of all, by digesting 
two parts of sulphuret of antimony, at a mo- 
derate heat, with three parts of oil of vitriol. 
This insoluble subsulphate being well washed, 



is then digested in a quantity of boiling water 
with its own weight of cream of tartar, and 
evaporated to the density of 1.161, after 
which it is filtered hot On cooling, crystals 
of the triple tartrate are obtained. One might 
imagine, that there is a chance of obtaining by 
this process a mixture of sulphate of potash, 
and perhaps of a triple sulphate of antimony, 
along with the tartar emetic. Probably this 
does not happen ; for it is said to yield crys- 
tals, very pure, very white, and without any 
mixture whatever. 

Pure tartar emetic is in colourless and 
transparent tetrahedrons or octohedrons. It 
reddens litmus. Its taste is nauseous and 
caustic. Exposed to the air, it effloresces 
slowly. Boiling water dissolves half its 
weight, and cold water a fifteenth part. 
Sulphuric, nitric, and muriatic acids, when 
poured into a solution of this salt, precipitate 
its cream of tartar ; and soda, potash, ammo- 
nia, or their carbonates, throw down its oxide 
of antimony. Baryta, strontia, and lime wa- 
ters, occasion not only a precipitate of oxide 
of antimony, like the alkalis, but also in- 
soluble tartrates of these earths. That pro- 
duced by the alkaline hydrosulphurets is 
wholly formed of kertnes ; while that caused 
by sulphuretted hydrogen contains both ker- 
mes and cream of tartar. The decoctions 
of several varieties of cinchona, and of seve- 
ral bitter and astringent plants, equally de- 
compose tartar emetic ; and the precipitate 
then always consists of the oxide of anti- 
mony, combined with the vegetable matter 
and cream of tartar. Physicians ought there- 
fore to beware of such incompatible mixtures. 
When tartar emetic is exposed to a red heat, 
it first blackens, like all organic compounds, 
and afterwards leaves a residuum of metallic 
antimony and subcarbonate of potash. From 
this phenomenon, and the deep brownish-red 
precipitate by hydrosulphurets, this antimo- 
nial combination may readily be recognized. 
The precipitate may further be dried on a 
filter, and ignited with black flux, when a 
globule of metallic antimony will be ob- 
tained. Infusion of galls is an active pre- 
cipitant of tartar emetic. 

This salt, in an undue dose, is capable of 
acting as a poison. The best antidotes are 
demulcent drinks, infusions of bark, tea, and 
sulphuretted hydrogen water, which instantly 
converts the energetic salt into a relatively 
mild sulphuret: anodynes are useful after- 
wards. The powder of tartar emetic, mixed 
with hog's lard, and applied to the skin of the 
human body, raises small vesications. 

The composition of this salt, according to 
M. Thenard, is 35.4 acid, 39.6 oxide, 16.7 
potash, and 8.2 water. The presence of the 
latter ingredient is obvious, from the undis- 
puted phenomenon of efflorescence. By a 
recent analysis of Mr Philips, this salt is 
composed of 



ANTIMONY. 



171 



ANTIMONY. 



1 atom bitartrate of potash, 22.5 49.58 
3 atoms protoxide of antimony, 19.5 42.97 
3 atoms water, 3.375 7.45 

100.00 

Dr Thomson, however, assigns only 2 
atoms of water, from his researches published 
in his work on the first principles of Chemis- 
try. Their atomic number for the oxide of 
antimony is one- half of mine. 

The deutoxide seems to have the property 
of combining with sulphur in various pro- 
portions. To this species of compound must 
be referred the liver of antimony, glass of 
antimony, and crocus metallorum of the an- 
cient apothecaries. According to M. Sou- 
beiran, glass of antimony contains protoxide 
(deutoxide of Berz.) 91.5, silica 4.5, per- 
oxide of iron 3.2, sulphuret of antimony 
1.9. Sulphuretted hydrogen fofms, with the 
deutoxide of antimony, a compound which 
possessed at one time great celebrity in medi- 
cine, and of which a modification has lately 
been introduced into the art of calico-printing. 
By dropping hydrosulphuret of potash, or of 
ammonia, into the cream tartrate, or into mild 
muriate of antimony, the hydrosulphuret of 
the metallic oxide precipitates of a beautiful 
deep orange colour. This is kermes mineral. 
Cluzel's process for obtaining a fine kermes, 
light, velvety, and of a deep purple-brown, is 
the following: One part of pulverized sul- 
phuret of antimony, 22 parts of crystallized 
subcarbonate of soda, and 200 parts of wa- 
ter, are to be boiled together in an iron pot. 
Filter the hot liquor into warm earthen pans, 
and allow them to cool very slowly. At the 
end of 24 hours the kermes is deposited. 
Throw it on a filter, wash it with water which 
had been boiled and then cooled out of con- 
tact with air. Dry the kermes at a tempera- 
ture of 85, and preserve in corked phials. 
Whatever may be the process employed, by 
boiling the liquor, after cooling and filtration, 
on new sulphuret of antimony, or upon that 
which was left in the former operation, this 
new liquid will deposit, on cooling, a new 
quantity of kermes. Besides the hydrosul- 
phuretted oxide of antimony, there is formed 
a sulphuretted hydrosulphuret of potash or 
soda. Consequently, the alkali seizes a por- 
tion of the sulphur from the antimonial sul- 
phuret, water is decomposed, and whilst a 
portion of its hydrogen unites to the alkaline 
sulphuret, its oxygen, and the other portion 
of its hydrogen, combine with the sulphuret- 
ted antimony. It seems, that the resulting 
kermes remains dissolved in the sulphuretted 
hydrosulphuret of potash or soda ; but as it 
is less soluble in the cold than the hot, it is 
partially precipitated by refrigeration. If 
we pour into the supernatant liquid, after the 
kermes is deposited and removed, any acid, 
as the dilute nitric, sulphuric, or muriatic, 
we decompose the sulphuretted hydrosulphu- 



ret of potash or soda. The alkaline base 
being laid hold of, the sulphuretted hydrogen 
and sulphur to which they were united are 
set at liberty ; the sulphur and kermes fall to- 
gether, combine with it, and form an orange- 
coloured compound, called the golden sul- 
phuret of antimony. It is a hydroguretted 
sulphuret of antimony. Hence, when it is 
digested with warm muriatic acid, a large 
residuum of sulphur is obtained, amounting 
sometimes to 12 per cent. Kermes is com- 
posed, by Thenard, of 20.3 sulphuretted hy- 
drogen, 4.15 sulphur, 72.76 oxide of anti- 
mony, 2.79 water and loss; and the golden 
sulphuret consists of 17.87 sulphuretted 
hydrogen, 68.3 oxide of antimony, and 12 
sulphur. M. Rose apparently proves, that 
kermes is the same as the native sulphuret 
of antimony. See above. 

By evaporating the supernatant kermes 
liquid, and cooling, crystals form, which have 
been lately employed by the calico printer to 
give a topical orange. These crystals are dis- 
solved in water, and the solution being thick- 
ened with paste or gum, is applied to cloth 
in the usual way. After the cloth is dried, 
it is passed through a dilute acid, when the 
orange precipitate is deposited and fixed on 
the vegetable fibres. 

An empirical antimonial medicine, called 
James's powder, has been much used in this 
country. The inventor called it his fever 
powder, and was so successful in his practice 
with it, that it obtained very great reputation, 
which it still in some measure retains. Pro- 
bably the success of Dr James was in great 
measure owing to his free use of the bark, 
which he always gave as largely as the sto- 
mach would bear, as soon as he had com- 
pletely evacuated the primae viae by the use 
of his antimonial preparation, with which at 
first he used to combine some mercurial. His 
specification, lodged in Chancery, is as fol- 
lows : " Take antimony, calcine it with a 
continued protracted heat, in a flat, unglazed, 
earthen vessel, adding to it from time to time 
a sufficient quantity of any animal oil and 
salt, well dephlegmated ; then boil it in 
melted nitre for a considerable time, and 
separate the powder from the nitre by dis- 
solving it in water." The real recipe has 
been studiously concealed, and a false one 
published in its stead. Different formulas 
have been offered for imitating it. That of 
Dr Pearson furnishes a mere mixture of an 
oxide of antimony with phosphate of lime. 
The real powder of James, according to this 
chemist, consists of 57 oxide of antimony, with 
43 phosphate of lime. It seems highly pro- 
bable that superphosphate of lime would act 
on oxide of antimony in a way somewhat simi- 
lar to cream of tartar, and produce a more che- 
mical combination than what can be derived 
from a precarious ustulation, and calcination, 
of hartshorn shavings and sulphuret of anti- 



ANTIMONY. 



172 



A PL O ME. 



raony, in ordinary hands. The antimonial 
medicines are powerful deobstruents, pro- 
moting particularly the cuticular discharge. 
The union of this metallic oxide with sul- 
phuretted hydrogen, ought undoubtedly to fa- 
vour its medicinal agency in chronic diseases 
of the skin. The kermes deserve more credit 
than it has hitherto received -from British 
physicians. 

The compounds formed by the antimoni- 
ous and antimonic acids with the bases, have 
not been applied to any use. Muriate of 
baryta may be employed as a test for tartar 
emetic. It will shew, by a precipitate inso- 
luble in nitric acid, if sulphate of potash be 
present. If the crystals be regularly formed, 
mere tartar need not be suspected. 

For its ores, saline compounds, and the 
reduction of the metals, see ORES, and SALT. 

A fulminating antimonic powder has been 
prepared by M. Serullas in the following man- 
ner. Grind carefully together 100 parts of 
tartar emetic and 3 parts of lamp-black, or 
ordinary charcoal powder. Crucibles capa- 
ble of holding about 3 ounces of water, to 
be only three-fourths filled, are to be ground 
smooth on their edges, and rubbed inside 
with powdered charcoal, so as to dust lightly 
their surface, and prevent the subsequent 
adherence of the carbonaceous cone which 
remains after the calcination. The above 
mixture being introduced into the crucible, 
is to be covered with a layer of powdered 
charcoal ; and the joinings of the cover must 
be luted. After exposure for 3 hours to a 
good heat in a reverberatory furnace, the 
crucible must be removed, and left to cool 
for 6 or 7 hours. This interval of time is 
necessary to allow the air, which always 
penetrates a little way into the crucibles, to 
burn the exterior coat of the fulminating 
mass ; otherwise, if it be taken out too re- 
cently, there is always an explosion. We 
must then hastily enclose it, without break- 
ing, into a glass with a wide opening. After 
some time it spontaneously breaks down into 
fragments of different sizes, retaining all its 
properties for years. When the calcination 
has been conducted as above, the product is 
excessively fulminating, so that, without the 
least compression, it gives rise to a violent 
detonation on contact with water. 1 00 parts 
of antimony, 75 of carburetted cream of tar- 
tar, and 12 of lamp-black, triturated together, 
form also an excellent mixture. A piece of 
the size of a pea of this fulminating com- 
pound, introduced into a mass of gunpowder, 
explodes it when thrown into water. It is 
to the presence of potassium that the above 
explosive property is due. 60 parts of car- 
buretted cream of tartar, 120 of bismuth, and 
1 of nitre, treated as above, yield an alloy 
very rich in potassium, of which the smallest 
portion cut with scissars sparkles. When 



bruised, it melts and burns. Ann. de Chim. 
Oct. 1822. 

ANTS. See ACID ( FORMIC). 

APATITE. Phosphate of lime. This 
mineral occurs both massive and crystallized. 
The crystals are six-sided prisms, low, and 
sometimes passing into the six-sided table. 
Lateral edges frequently truncated, and the 
faces smooth. Lustre splendent. Translu- 
cent, rarely transparent. Scratched by fluor- 
spar. Brittle. Colours, white, wine-yellow, 
green, and red. Sp. gr. 3.1. Phospho- 
resces on coals. Electric by heat and friction. 
Consists of 53.75 lime + 46.25 phosphoric 
acid, by Klaproth's analysis of the variety 
called asparagus stone. It occurs in primi- 
tive rocks ; in the tin veins of the granite of 
St Michael's Mount, Cornwall; near Chud- 
leigh in Devonshire; at Nantes in France; 
in St Gothard, and in Spain ; and with mo- 
lybdena in granite, near Colbeck, Cumber- 
land. Phosphorite is massive, forming great 
beds in the province of Estremadura. Yel- 
lowish-white colour. Dull or glimmering 
lustre. Semi-hard. Fracture imperfect; 
curve foliated. Brittle. Sp. gr. 2.8. Phos- 
phorescent with heat. Its composition, by 
Pelletier, is 59 lime, 34 phosphoric acid, 1 
carbonic acid, 2.5 fluoric acid, 2 silica, 1 
oxide of iron, and 0.5 muriatic acid. 

APHLOGISTIC LAMP. One which 
burns without flame. See COMBUSTION. 

APHANITE.* This is the name given 
by Haiiy to a rock apparently homogeneous, 
but really compound, in which amphibole is 
the predominant principle. It is a green- 
stone, the distinction of whose parts is indis- 
cernible. Aphanite is included among the 
rocks which the older mineralogists called 
corneennes, or lapis corneus trapezius. 

APHRITE. Earth foam ; schaumerde. 
This carbonate of lime occurs usually in a 
friable state ; but sometimes solid. Colour, 
almost silver-white. Massive, or in fine par- 
ticles. Shining lustre, between semi-metal- 
lic and pearly. Fracture, curve foliated. 
Opaque; soils a little. Very soft, and 
easily cut. Feels fine and light. It is 
usually found in calcareous veins, at Gera 
in Misnia, and Eisleben in Thuringia. It 
consists, by Bucholz, of 51.5 lime, 39 acid, 
1 water, 5.7 silica, 3.3 oxide of iron. 

APH RIZITE. A variety of black tour- 
maline. 

A PL O M E . This is commonly considered 
to be a variety of the garnet; but the diffe- 
rence between these minerals is this : The 
planes of the aplome dodecahedrons are stri- 
ated parallel with their smaller diagonal, 
which, according to Haiiy, indicates the pri- 
mitive form to be a cube, and not a dodeca- 
hedron. Its colour is deep orange- brown. 
It is opaque, and harder than quartz. Sp. 



* Non manifestos. 



ARABIC (GUM). 



173 



ARCHIL. 



gr. is much less than garnet, viz. 3.4-4-. It 
consists, by Laugier's analysis, of 40 silica, 
20 alumina, 14*. 5 lime, 14 oxide of iron, 2 
oxide of manganese, 2 silica and iron. It 
is fusible into a black glass, while garnet 
fuses into a black enamel. It is found on 
the river Lena in Siberia, and also in New 
Holland. 

APOPHYLLITE. Ichthyophthalmite. 
Fish-eye stone. It is found both massive 
and crystallized. It occurs in square prisms, 
whose solid angles are sometimes replaced by 
triangular planes, or the prisms are termi- 
nated by pyramids consisting of 4 rhomboi- 
dal planes. Structure lamellar ; cross frac- 
ture, fine-grained, uneven. External lustre, 
splendent and peculiar ; internal, glistening 
and pearly. Semitransparent, or translucent. 
Moderately hard, and easily broken. Sp. gr. 
2.49. It exfoliates, then froths, and melts 
into an opaque bead, before the blowpipe. It 
consists of 51 silica, 28 lime, 4 potash, 17 
water Vauquelin. It is found in the iron 
mine of Utoe in Sweden, at the copper mine 
of Fahlun, at Arendahl, Faroe, the Tyrol ; 
and Dr MacCulloch met with a solitary crys- 
tal in Dunvegan, in the Isle of Skye. 

APPARATUS. See LABORATORY. 

APPLES. The juice of apples seems to 
be composed of much water, a small quantity 
of sugar analogous to that of the grape, a 
very small quantity of fermentescible matter, 
a large quantity of mucilage, with malic and 
acetic acids. There is no tartar in apples. 
See CYDER, and ACID (MALIC). 

APYROUS. Bodies which sustain the 
action of a strong heat for a considerable time, 
without change of figure or other properties, 
have been called apyrous ; but the word is 
seldom used in the art of chemistry. It is 
synonymous with refractory. 

AQUAFORTIS. This name is given 
to a weak and impure nitric acid, commonly 
used in the arts. It is distinguished by the 
terms double and single, the single being only 
half the strength of the other. The artists 
who use these acids call the more concen- 
trated acid, which is much stronger even 
than the double aquafortis, spirit of nitre. 
See ACID ( NITRIC). 

AQUA MARINE. See BERYL. 

AQUA REGIA or REGIS. This acid, 
being compounded of a mixture of the nitric 
and muriatic acids, is now termed by chemists 
nitro-muriatic acid. 

AQUA VIT^:. Ardent spirit of the first 
distillation has been distinguished in commerce 
by this name. The distillers of malt and me- 
lasses spirits call it low wines. 

AQUILA ALBA. One of the names 
given to the combination of muriatic acid and 
mercury, in that state which is commonly 
known by the denomination of mercurius 
dulcis, calomel, or mild muriate of mercury. 

ARABIC (GUM). This is reckoned the 



purest of gums, and does not greatly differ 
from gum-senegal, vulgarly called gum-se- 
neca, which is supposed to be the strongest, 
and is on this account, as well as its greater 
plenty and cheapness, mostly used by calico 
printers and other manufacturers. The gums 
of the plum and the cherry-tree have nearly 
the same qualities as gum-arabic. All these 
substances facilitate the mixture of oils with 
water. By my analysis, gum-arabic is com- 
posed in 100 parts of 35.13 carbon, 6.08 
hydrogen, 55.79 oxygen, and possibly 3 of 
azote. 

ARABLE LANDS. It is a problem in 
chemistry, and by no means one of the least 
importance to society, to determine what are 
the requisites which distinguish fruitful lands 
from such as are less productive. See SOILS, 
and ANALYSIS of SOILS. 

ARBOR DIAN^E. See SILVER. 

ARCHIL, ARCHILLA, ROCELLA, 
ORSEILLE. A whitish lichen, growing 
upon rocks in the Canary and Cape Verd 
Islands, which yields a rich purple tincture, 
fugitive indeed, but extremely beautiful. 
This weed is imported to us as it is gathered. 
Those who prepare it for the use of the dyer 
grind it betwixt stones, so as thoroughly to 
bruise, but not to reduce it into powder, and 
then moisten it occasionally with a strong 
spirit of urine, or urine itself mixed with 
quicklime : in a few days it acquires a pur- 
plish-red, and at length a blue colour ; in the 
first state it is called archil, in the latter lac- 
mus or litmus. 

The dyers rarely employ this drug by it- 
self, on account of its dearness, and the 
perishableness of its beauty. The chief use 
they make of it is for giving a bloom to other 
colours, as pinks, c. This is effected by 
passing the dyed cloth or silk through hot 
water slightly impregnated with the archil. 
The bloom thus communicated soon decays 
upon exposure to the air. M. Hellot in- 
forms us, that by the addition of a little so- 
lution of tin, this drug gives a durable dye ; 
that its colour is at the same time changed 
toward a scarlet ; and that it is the more per- 
manent, in proportion as it recedes the more 
from its natural colour. 

Prepared archil very readily gives out its 
colour to water, to volatile spirits, and to al- 
cohol ; it is the substance principally made 
use of for colouring the spirits of thermome- 
ters. As exposure to the air destroys its co- 
lour upon cloth, the exclusion of the air pro- 
duces a like effect in those hermetically sealed 
tubes, the spirits of large thermometers be- 
coming in a few years colourless. The Abbe 
Nollet observes, (in the French Memoirs for 
the year 1742), that the colourless spirit, upon 
breaking the tube, soon resumes its colour, 
and this for a number of times successively ; 
that a watery tincture of archil, included in 
the tubes of thermometers, lost its colour in 



AROMATICS. 



174 



ARSENIC. 



three days ; and that in an open deep vessel 
it became colourless at the bottom, while the 
upper part retained its colour. 

A solution of archil in water, applied on 
cold marble, stains it of a beautiful violet or 
purplish-blue colour, far more durable than 
the colour which it communicates to other 
bodies. M. du Fay says he has seen pieces 
of marble stained with it, which in two years 
had suffered no sensible change. It sinks 
deep into the marble, sometimes above an 
inch, and at the same time spreads upon the 
surface, unless the edges be bounded by wax 
or some similar substance. It seems to make 
the marble somewhat more brittle. 

There is a considerable consumption of an 
article of this kind manufactured in Glasgow 
by Mr Macintosh. It is much esteemed, 
and sold by the name of cudbear. We have 
seen beautiful specimens of silk thus dyed, 
the colours of which were said to be very 
permanent, of various shades, from pink and 
crimson to a bright mazarine blue. 

Litmus is likewise used in chemistry as a 
test, either staining paper with it, or by in- 
fusing it in water, when it is very commonly, 
but with great impropriety, called tincture of 
turnsole. The persons by whom this article 
was prepared formerly gave it the name of 
turnsole, pretending that it was extracted 
from the turnsole, heliotropium tricoccum, in 
order to keep its true source a secret. The 
tincture should not be too strong, otherwise 
it will have a violet tinge, which, however, 
may be removed by dilution. The light of 
the sun turns it red even in close vessels. It 
may be made with spirit instead of water. 
This tincture, or paper stained with it, is 
presently turned red by acids ; and if it be 
first reddened by a small quantity of vinegar, 
or some weak acid, its blue colour will be re- 
stored by an alkali. 

ARCTIZITE. See WERNERITE. 

ARDENT SPIRIT. See ALCOHOL. 

A REND ATE, See PISTACITE. 

AREOMETER. See HYDROMETER. 

ARFWEDSONITE. A ferruginous va- 
riety of hornblende. Colour black ; cleav- 
age, planes much more brilliant than those of 
hornblende, which scratches it. Sp. gravity 
3.44. It sometimes accompanies the sodalite 
from Greenland. 

ARGAL. Crude tartar, in the state in 
which it is taken from the inside of wine ves- 
sels, is known in the shops by this name. 

ARGENTATE OF AMMONIA. Ful- 
minating silver. 

ARGENTINE FLOWERS OF AN- 
TIMONY. The deutoxide of the English 
chemists, or the antimonious acid. 

ARGILLACEOUS EARTH. See ALU- 
MINA. 

ARGILLITE. See CLAY-SLATE. 

AROMATICS. Plants which possess a 
fragrant smell united with pungency, and at 



the same time are warm to the taste, are call- 
ed aromatics. Their peculiar flavour appears 
to reside in their essential oil, and rises in dis- 
tillation either with water or spirit. See OILS 
(ESSENTIAL). 

ARRACK. A spirituous liquor import- 
ed from the East Indies. It is chiefly manu- 
factured at JBatavia, and at Goa upon the 
Malabar coast. 

ARRAGONITE. This mineral occurs 
massive, in fibres of a silky lustre, and in the 
form of fibrous branches, diverging from a 
centre, Flos-ferri* It is frequently crystal- 
lized in what appear at first sight to be regu- 
lar six-sided prisms. On close inspection a 
longitudinal crack will be observed down each 
lateral face. It occurs also in elongated oc- 
tohedrons. Lustre glassy, fracture foliated 
and fibrous. Colours greenish and pearl- 
grey ; often violet and green in the middle ; 
and arranged in the direction of the fibres, so 
that the longitudinal fibres are green, the 
transverse violet-blue. Double cleavage 
translucent ; refracts doubly ; scratches cal- 
careous spar, and sometimes even glass ; brit- 
tle ; sp. grav. 2.90. It consists of carbonate 
of lime, with occasionally a little carbonate 
of strontia. It is found in Arragon in 
Spain ; at Leogany in Salzburg ; at Marien- 
berg in Saxony ; Sterzing in the Tyrol ; and 
in the cavities of basalt near Glasgow. The 
finest specimens of the Flos-ferri ramifications 
come from the mines of Eisenerz in Stiria : 
beautiful specimens have been also found in 
the Dufton lead mines in England, in the 
workings of an old coal mine, called Lufton- 
hill pit, near Durham. It also occurs in the 
trap rocks of Scotland. 

ARROW ROOT. This fecula is obtained 
from the roots of the Maranta Arundinacea, 
a plant cultivated in the West Indies. The 
roots are washed, and beat to a pulp in large 
wooden mortars, which is afterwards separated 
from fibrous matter by agitation with water 
in large tubs. The milky liquor is passed 
through a sieve, and allowed to subside. 
When thoroughly washed and dried, it con- 
stitutes this nutritive species of starch, very 
analogous to well purified potato starch. 

ARSENIC, in the metallic state, is of a 
bluish-white colour, subject to tarnish, and 
grows first yellowish, then black, by exposure 
to air. It is brittle, and when broken exhi- 
bits a laminated texture. Its specific gravity 
is 5.763. In close vessels it sublimes entire 
at 356 F., but burns with a small flame if 
oxygen be present. 

The arsenic met with in commerce has 
the form of a white oxide. It is brought 
chiefly from the cobalt works in Saxony, 
where zaffre is made. Cobalt ores contain 
much arsenic, which is driven off by long 
torrefaction. The ore is thrown into a fur- 
nace, resembling a baker's oven, with a flue, 
or horizontal chimney, nearly two hundred 



ARSENIC. 



175 



ARSENIC. 



yards long, into which the fumes pass, and 
are condensed into a greyish or blackish pow- 
der. This is refined by a second sublimation 
in close vessels, with a little potash to detain 
the impurities. As the heat is considerable, 
it melts the sublimed flowers into those crys- 
talline masses which are met with in com- 
merce. See ACID (ARSENIOUS). 

The metal may be obtained from this, 
either by quickly fusing it together with twice 
its weight of soft soap and an equal quantity 
of alkali, and pouring it out, when fused, in- 
to a hot iron cone ; or by mixing it in pow- 
der with oil, and exposing it in a matrass to a 
sand heat. This process is too offensive 
to be performed except in the open air, or 
where a current of air carries off the fumes. 
The decomposed oil first rises; and the ar- 
senic is afterwards sublimed in the form of a 
flaxy metallic substance. It may likewise be 
obtained by mixing two parts of the arsenious 
acid with one of black flux ; putting the 
mixture into a crucible with another inverted 
over it, and luted to it with clay and sand ; 
and applying a red heat to the lower crucible. 
The metal will be reduced, and line the in- 
side of the upper crucible. 

It is among the most combustible of the 
metals, burns with a blue flame and garlic 
smell, and sublimes in the state of arsenious 
acid. 

Chloride of Arsenic. One part of arsenious 
acid, with ten parts of concentrated sulphuric 
acid, is to be put into a tubulated retort, and 
the temperature raised to nearly 212 F. 
Fragments of fused common salt are then to 
be thrown in by the tubulure. By continuing 
the heat, with the successive addition of com- 
mon salt, protochloride of arsenic is obtained. 
It falls, drop by drop, from the beak of the re- 
tort, and may be collected in cooled vessels. 
Dumas, Ann. de Chimie, xxxiii. 360. 

Concentrated sulphuric acid does not at- 
tack arsenic when cold ; but if it be boiled 
upon this metal, sulphurous acid gas is emit- 
ted, a small quantity of sulphur sublimes, 
and the arsenic is reduced to an oxide. 

Nitric acid readily attacks arsenic, and 
converts it into arsenious acid, or, if much be 
employed, into arsenic acid. 

Boiling muriatic acid dissolves arsenic, but 
affects it very little when cold. This solution 
affords precipitates upon the addition of al- 
kalis. The addition of a little nitric acid ex- 
pedites the solution ; and this solution, first 
heated and condensed in a close vessel, is 
wholly sublimed into a thick liquid, formerly 
termed butter of arsenic. Thrown in powder 
into chlorine gas, it burns with a bright white 
flame, and is converted into a chloride. 

None of the earths or alkalis act upon it, 
unless it be boiled a long while in fine pow- 
der, In a large proportion of alkaline solu- 
tion. 

Nitrates detonate with arsenic, convert it 



into arsenic acid, and this, combining with 
the base of the nitrate, forms an arseniate, 
that remains at the bottom of the vessel. 

Muriates have no action upon it; but if 
three parts of chlorate of potash be mixed 
with one part of arsenic in fine powder, 
which must be done with great precaution 
and a very light hand, a very small quantity 
of this mixture, placed on an anvil, and 
struck with a hammer, will explode with 
flame and a considerable report : if touched 
with fire, it will burn with considerable rapi- 
dity; and if thrown into concentrated sul- 
phuric acid, at the instant of contact a flame 
rises into the air like a flash of lightning, 
which is so bright as to dazzle the eye. 

Arsenic readily combines with sulphur by 
fusion and sublimation, and forms a yellow 
compound called orpiment, or a red called 
realgar. The nature of these, and their dif- 
ference, are not accurately known ; but Four- 
croy considers the first as a combination of 
sulphur with the oxide, and the second as a 
combination of sulphur with the metal itself, 
as he found the red sulphuret converted into 
the yellow by the action of acids. 

In order to test the opinion entertained by 
certain physicians, that sulphuret of arsenic 
is innocuous, M. Orfila made several experi- 
ments with it, which shewed clearly its dele- 
terious nature. On applying 50 or 60 grains 
of the yellow sulphuret of arsenic to the 
thighs of dogs, these animals suffered in the 
same manner as by other arsenical prepara- 
tions, and died in from 48 to 60 hours. The 
native orpiment of Tojova poisoned and 
caused death in two days. Death was pro- 
duced in six days by 40 grains of native 
realgar from Harpnike in Transylvania. 
Hence it is shewn, that the sulphurets of ar- 
senic, either natural or artificial, and when 
free from white arsenic, are still poisonous. 
M. Orfila proved by similar experiments, 
that the sulphurets of lead, copper, and mer- 
cury, (red as well as black), were innocuous. 
Most metals unite with arsenic, which exists 
in the metallic state in such alloys as possess 
the metallic brilliancy. 

Iodine and arsenic unite, forming an 
iodide of a dark purple-red colour, possess- 
ing the properties of an acid. It is soluble 
in water, and its solution forms a soluble 
compound with potash. Arsenic combines 
with hydrogen into a very noxious com- 
pound, called arsenuretted hydrogen gas. 
To prepare it, fuse in a covered crucible three 
parts of granulated tin, and one of metallic 
arsenic in powder ; and submit this alloy, 
broken in pieces, to the action of muriatic 
acid in a glass retort. On applying a mo- 
derate heat, the arsenuretted hydrogen comes 
over, and may be received in a mercurial or 
water pneumatic trough. Protomuriate of 
tin remains in the retort. When one of 
arsenic is used for 15 of tin, the former metal 



ARSENIC. 



176 



ASBESTOS. 



is entirely carried off'in the evolved hydrogen. 
100 parts of this gas contain 140 of hydro- 
gen, as is proved by heating it with tin. Its 
specific gravity, according to Sir H. Davy, 
as 0.5552 ; according to Trommsdorf, 0.5293. 
Stromeyer states, that by a cold of 22 
it condenses into a liquid. Exploded with 
twice its bulk of oxygen, water and oxide of 
arsenic are formed. When arsenuretted hy- 
drogen issuing from a tube is set on fire, it 
deposits a hydruret of arsenic. Sulphur, 
potassium, sodium, and tin, decompose this 
gas, combine with its metal, and in the case 
of sulphur, sulphuretted hydrogen results. 
By subtracting from the specific gravity of 
the arsenuretted gas that of hydrogen gas X 
T5ir we nave tne proportion of arsenic pre- 
sent; 0.55520 0.09716 = 0.46804 = 
the arsenic in 100 measures of arsenuretted 
hydrogen ; which gives the proportion by 
weight of about 5 arsenic to 1 hydrogen ; but 
Stromeyer's analysis by nitric acid gives about 
50 arsenic to 1 hydrogen, which is probably 
much nearer the true composition. A prime 
equivalent of hydrogen is to one of arsenic as 
1 to 76; and two consequently as 1 to 38. 
Gehlen fell a victim to his researches on this 
gas ; and therefore the new experiments re- 
quisite to elucidate its constitution must be 
conducted with circumspection. If chlorine 
be added to a mixture of arsenuretted and 
sulphuretted hydrogen, the bulk diminishes, 
and yellow-coloured flakes are deposited. 
Concentrated nitric acid occasions an explo- 
sion in this gas, preceded by nitrous fumes ; 
but if the acid be diluted, a silent decom- 
position of the gas is effected. The density 
of the hydrogen in this compound gas is 
9.09716. Therefore, by Stromeyer's analysis, 
we have this proportion to calculate the spe- 
cific gravity of the gas; 2.19 : 0.09716 : : 
(2.19-j- 106) : 4.827; a quantity nearly 
9 times greater than what experiment has 
given. 

ITns gas extinguishes flame, and instantly 
destroys animal life. Water has no effect 
upon it. From the experiments of Sir H. 
Davy and MM. Gay Lussac and Thenard, 
there appears to be a solid compound of hy- 
drogen and arsenic, or a hydruret. It is 
formed by acting with the negative pole of a 
voltaic battery on arsenic plunged in water. 
It is reddish-brown, without lustre, taste, or 
smell. It is not decomposed at a heat ap- 
proaching to cherry-red ; but at this tempe- 
rature it absorbs oxygen, while water and 
arsenious acid are formed, with the evolution 
of heat and light. The proportion of the two 
constituents is not known. 

Arsenic is used in a variety of arts. It 
enters into metallic combinations wherein a 
white colour is required. Glass manufac- 
turers use it ; but its effect in the composi- 
tion of glass does not seem to be clearly ex- 
plained. Orpiment and realgar are used as 



pigments. See ACIDS ( ARSENIC and AHSE- 
NIOUS), and SALT. 

ASAFCETIDA is obtained from a large 
umbelliferous plant growing in Persia. The 
root resembles a large parsnep, externally of 
a black colour : on cutting it transversely, the 
asafoetida exudes in form of a white thick 
juice, like cream ; which, from exposure to 
the air, becomes yellower and yellower, and 
at last of a dark brown colour. It is very 
apt to run into putrefaction ; and hence those 
who collect it carefully defend it from the 
sun. The fresh juice has an excessively strong 
smell, which grows weaker and weaker upon 
keeping : a single dram of the fresh fluid 
juice smells more than a hundred pounds of 
the dry asafcetida brought to us. The Per- 
sians are commonly obliged to hire ships on 
purpose for its carriage, as scarcely any one 
will receive it along with other commodities, 
its stench infecting every thing that comes 
near it. 

The common asafoetida of the shops is of a 
yellowish or brownish colour, unctuous and 
tough, of an acrid or biting taste, and a 
strong disagreeable smell, resembling that of 
garlic. From four ounces Neumann obtain- 
ed, by rectified spirit, two ounces six drams 
and a half of resinous extract ; and after- 
ward, by water, three drams and half a 
scruple of gummy extract ; about six drams 
and a scruple of earthy matter remaining 
undissolved. On applying water at first, he 
gained, from four ounces, one ounce three 
scruples and a half of gummy extract 

Asafoetida is administered in nervous and 
hysteric affections, as a deobstruent, and 
sometimes as an anthelmintic. A tincture of 
it is kept in the shops, and it enters into the 
composition of the compound galbanum pill 
of the London college, the gum pill of for- 
mer dispensatories. 

ASBESTOS or ASBESTUS. A mine- 
ral of which there are five varieties, all more 
or less flexible and fibrous. 

1. Amianthus occurs in very long, fine, 
flexible, elastic fibres, of a white, greenish, or 
reddish colour. It is somewhat unctuous to 
the touch, has a silky or pearly lustre, and is 
slightly translucent. Sectile ; tough ; sp. gr. 
from 1 to 2.3. Melts with difficulty before 
the blowpipe into a white enamel. It is 
usually found in serpentine in the Taren- 
taise in Savoy.; in long and beautiful fibres 
in Corsica ; near Bareges in the Pyrenees ; 
in Dauphiny and St Gothard ; at St Ke- 
verne, Cornwall ; at Portsoy, Scotland ; in 
mica slate at Glenelg, Inverness-shire ; and 
near Durham. It consists of 59 silex, 25 
magnesia, 9.5 lime, 3 alumina, and 2.25 
oxide of iron. 

The ancients manufactured cloth out of 
the fibres of asbestos, for the purpose, it is 
said, of wrapping up the bodies of the dead 
when exposed on the funeral pile. Several 



ASHES. 



177 



ASPHALTUM. 



moderns have likewise succeeded in making 
this cloth ; the chief artifice of which seems 
to consist in the admixture of flax and a 
liberal use of oil ; both which substances are 
afterwards consumed by exposing the cloth 
for a certain time to a red heat. Although 
the cloth of asbestos, when soiled, is restored 
to its primitive whiteness by heating in the 
fire ; it is found, nevertheless, by several 
authentic experiments, that its weight dimi- 
nishes by such treatment. The fibres of 
asbestos, exposed to the violent heat of the 
blowpipe, exhibit slight indications of fusion ; 
though the parts, instead of running together, 
moulder away, and part fall down, while the 
rest seem to disappear before the current of 
air. Ignition impairs the flexibility of as- 
bestos in a slight degree. 

2. Common asbestus occurs in masses of 
fibres of a dull greenish colour, and of a 
somewhat pearly lustre. Fragments splin- 
tery. It is scarcely flexible, and greatly 
denser than amianthus. It is slightly unc- 
tuous to the touch. Sp. grav. 2.7. Fuses 
with difficulty into a greyish-black scoria. 
It is composed of 63.9 silica, 16 magnesia, 
12.8 lime, 6 oxide of iron, and 1. 1 alumina. 
It is more abundant than amianthus, and is 
found usually in serpentine, as at Portsoy, 
the Isle of Anglesea, and the Lizard in Corn- 
wall. It was found in the limestone of 
Glentilt by Dr M'Culloch, in a pasty state, 
but it soon hardened by exposure to air. 

3. Mountain Leather consists not of pa- 
rallel fibres like the preceding, but interwo- 
ven and interlaced so as to become tough. 
When in very thin pieces, it is called moun- 
tain paper. Its colour is yellowish-white, 
and its touch meagre. It is found at Wan- 
lockhead in Lanarkshire. Its specific gravity 
is uncertain. 

4-. Mountain Cork, or Elastic Asbestus, is, 
like the preceding, of an interlaced fibrous 
texture ; is opaque ; has a meagre feel and 
appearance, not unlike common cork, and 
like it, too, is somewhat elastic. It swims 
on water. Its colours are, white, grey, 
and yellowish-brown. Receives an impres- 
sion from the nail ; very tough ; cracks when 
handled, and melts with difficulty before the 
blowpipe. Sp. grav. from 0.68 to 0.99. 
It is composed of silica 62, carbonate of 
lime 12, carbonate of magnesia 23, alumina 
2.8, oxide of iron 3. 

5. Mountain Wood. Ligniform asbestus 
is usually massive, of a brown colour, and 
having the aspect of wood. Internal lustre 
glimmering. Soft, sectile, and tough ; op- 
aque ; feels meagre ; fusible into a black 
slag. Sp. grav. 2.0. It is found in the Ty- 
rol ; Dauphiny ; and in Scotland, at Glentilt, 
Portsoy, and Kildrumie. 

ASHES. The fixed residue of combus- 
tible